LGBT characters

A number of people have been identified as (or implied to be) lesbian, gay, bisexual or transgender (commonly abbreviated LGBT).

Lesbian

 * Patty Bouvier - Formerly closeted, as she appeared (enclosed) on a float in a gay pride parade, chanting "We're gay! We're glad! But don't tell Mom and Dad!" along with Waylon Smithers, Jr.. As time went by, her orientation became more or less an open secret, until she came out to everybody (including, finally, Marge) when she almost married Veronica.
 * and Anne Heche - When the Simpsons visited Hollywood, they took a "celebrity tour" and saw Ellen and Anne sitting together in their porch swing.
 * Verity Heathbar - Leaves her husband Charles for Patty, who says that they were brought together by their hatred of Homer.
 * Billie Jean King, Susan Sontag and Sappho of Lesbos - Lisa cited the three of them as heroes of hers who are or were gay.
 * Miss Viola - Lives in a country house near Springfield, along with her wife. When Abe and young Homer took Bongo (Homer's childhood dog) to their house, Abe thought that Viola's wife was her husband, annoying both women.
 * Jóhanna Sigurðardóttir - When Homer was giving a speech to the people of Iceland (in defense of Carl), he mentioned Iceland having a lesbian prime minister, which made Sigurðardóttir roll her eyes.
 * Megan Matheson - Is in a committed relationship with her girlfriend, the former Miss Denmark.

Hinted to be Lesbian

 * - hinted as being attracted to the assistant librarian as she had a one-night stand with her in the viewing room.
 * - Kissed Marge on the lips after she realized that Marge didn't like human contact.
 * Peppermint Patty - Lisa cited her as being among heroes of hers who are or were gay, but qualified her statement by adding that she only suspected that Peppermint Patty was gay.
 * Valerie - After she met Lisa, she held Lisa's hands, implying to Lisa that she wanted to be more than just friends.

Openly gay characters

 * Waylon Smithers, Jr. - Longtime closeted, now openly gay. There was a long-standing running gag on the show revolving around references to Smithers' orientation (or at least his fixation on Mr. Burns) and his efforts to keep it a secret. One blatant example occurred when Smithers booted up his home computer and an animation of Mr. Burns appeared, saying (in obviously cobbled-together sound clips), "Hello, Smithers. You're quite good at turning me on." Smithers then said to Lisa (who was standing behind him), "You should probably ignore that." Smithers finally came out when he sang a ballad about his unrequited love for Mr. Burns in the Springfield Nuclear Power Plant, which came as no surprise to anyone who worked there.
 * The show has treated Smithers as openly gay since then, for example, with Marge referring to him as her "gay best friend".
 * Despite this, Mr. Burns' awareness of Smithers' sexuality seems to fluctuate occasionally but remains unknown to anyone but himself. However since this usually happens in The Simpsons: Tapped Out, considered non-canonical, it should be taken with somewhat of a grain of salt.
 * - A nostalgia store owner who befriends the Simpson family.
 * Roscoe - Manager of the Ajax Steel Mill. He and his workers are all gay, and at breaks they turn the mill into a gay nightclub.
 * Grady and Julio - Were a couple when Homer roomed with them. They evidently broke up sometime after that, as Julio later married Thad. Later still, Julio and Thad separated, and Julio and Grady got back together.
 * - Hangs out in the Gay Neighborhood and knows Waylon Smithers, Jr. quite well. When he saw Smithers with Homer, he thought that Homer was the "Mr. Burns that [Smithers was] always talking about".
 * Thad - Married Julio (with Homer as the officiant) subsequent to Julio's and Grady's breakup. They apparently later separated.
 * Dewey Largo - Formerly in the closet, now openly gay.
 * He was in a many-vehicle car crash and was rescued from the same car as Waylon Smithers, Jr.; then was quick to state that they were just carpooling.
 * He later had Nelson Muntz customize a bicycle for him and brought it back complaining that it fell apart during a pride parade. When Nelson asked what kind of pride, Largo sharply replied, "Never you mind!".
 * Largo revealed himself as gay when he ran off with his soul mate, a man he met at Mo's, also named Dewey.
 * Dewey - Former boyfriend of Dewey Largo; their attraction to each other started when they found they had the same first name. They later broke up.
 * Geoffrey - Current boyfriend of Dewey Largo.
 * Grizzly Shawn - a patron of Mo's Bar. He fancied Moe. He is also a friend of Julio and Grady and later married.
 * Comic Book Gay - Patron of Mo's and cousin of Comic Book Guy, to whom he bears a strong enough resemblance that Homer mistook him for Comic Book Guy. Told Homer that he liked comic books of "a certain kind".
 * Kissing cops - When the Simpson family were on the run during Trappuccino, they stayed at the Red Rash Inn. The two cops drove up to Marge and she thought she was going to be arrested. Instead, they walked past her, went into a room and started kissing each other.
 * Contractor - When Homer botched a home remodeling job, Marge hired a contractor to do it. Homer, however, felt threatened by the contractor's presence and sarcastically asked why he didn't just kiss Marge. The contractor replied that he was gay, but had a subcontractor (Angelo) who would take care of that.
 * - Husband of Grizzly Shawn.

In the closet

 * Gay Latino man - When he saw Homer's graffiti tag of "El Homo"(parodying "El Barto"), he interpreted it as Homer declaring himself to be homosexual, and said, "If only I had your courage, Señor."
 * Huckleberry Hound - Once said that he was gay but couldn't tell anyone. However, because he made that statement in a non-canon episode, that piece of information should also be considered non-canon.

Hinted to be Gay

 * Lenny Leonard - Sometimes hinted as being attracted to Carl.
 * Carl Carlson - Sometimes hinted as being attracted to Lenny.
 * KarlKissesHomer.JPG[[Karl]] - Kissed Homer on the lips after stating that his mom taught him to never kiss a fool. However, it should be noted that Karl is implied to be of German origin, and men kissing men doesn't necessarily equate to homosexuality as much as just respect in some European countries. Karl also patted Homer on the behind after giving him a pep talk, but in the context of the situation it could easily be considered a comradely gesture rather than an affectionate one. Further clouding the issue is that Karl was friends with the women in the power plant's typing pool, and, after being fired, made a point of returning to say goodbye to them. However, it isn't known whether he was romantically involved with any of them. There is a lot of ambiguity surrounding the issue of Karl's sexual orientation, and not enough information to definitively settle the question. A stronger hint at Karl's possible orientation is dropped when Karl is seen supporting Moe's campaigning as gay while running for city council, but there's still no overt indication of his status.
 * Sea Captain - In The Simpsons: Tapped Out, he implied that he is homosexual. In the game, he suggests that Ned Flanders is gay after Ned gives him decorating advice. Ned states that he is not homosexual, to which the Sea Captain responds, "Neither am I, wink-wink. Now let's get to decorating, Girlfriend." However, there seem to be no other implications that the Sea Captain is gay. Also, because Tapped Out is non-canon, this piece of information cannot be construed as a definitive statement regarding the Sea Captain's orientation.
 * Dr. Smith actor at the Bi-Mon-Sci-Fi-Con - Implied that he wanted to molest Bart Simpson. It is important to note, however, that tendencies toward paedophilia (even same-sex paedophilia) don't automatically equate to homosexuality.
 * Rod Flanders and Todd Flanders - Shown to be gay in the future; Ned feels that he owes Bart a favor (and agrees to lend Bart money) because Bart hasn't outed them. However, due to the future setting, this information should be considered non-canon.
 * Discus Stu - Was among a group of suitors waiting to see Penelope. He cut to the front of the line and said, "Discus Stu has for two-zo", referring to the alcoholic beverage he was carrying. Penelope's son Telemachus, pleased at the prospect of his mother having a date, said he would leave the two of them alone. Discus Stu then gestured at Telemachus and said, "Discus Stu was talking to you!" which elicited a shudder from Telemachus. (Due to the non-canon setting, Discus Stu's hinted orientation has no bearing on that of his canon counterpart, Disco Stu.)
 * Raoul - Lives in Miami Beach and met Abraham Simpson while Abe was visiting. Said that women disgusted him, but appeared to be physically attracted to Abe.
 * Tab Spangler - Counselor at the Serenity Ranch fat camp. When he drives Homer from Springfield to Serenity Ranch for some treatment, he suggests that they stop off at a motel and split a room, even though it's only an hour's drive. When Homer asks where he's going to sleep, Spangler replies, "We can worry about that when we're standing naked before the bed!" Also, in one of his treatment exercises, Spangler's fat camp clients pull a chariot while he rides in it. The chariot is called the "Chubby Chaser", which in the gay community is a term for a man who is attracted to overweight men.
 * Paul Lynde - Appeared in an Easter-themed TV special with Nadia Comăneci. Lynde, dressed in a rabbit costume and speaking in a blatantly suggestive manner, said to Comăneci that he would like to "hippity-hop on [her] balance beam". Comăneci shuddered in disgust, then recovered her composure and drily replied, "I don't think you understand the mechanics of heterosexual sex."
 * - When Marge asked Lisa which friend she would like to take to Ned Flanders' beach house, Lisa replied that her only friends were grown-up nerds like Gore Vidal. She then went on to lament that even Vidal had kissed more boys than she ever would.
 * Rod and Todd's and David - When Marge knocked out Ned Flanders, Rod and Todd were worried he was going to die and they would have to be raised by their Uncle Kevin and "his funny friend David", implying that they are homosexual lovers.
 * Cameron and Tyler Winklevoss - After coming in second in a London 2012 Olympics boat rowing event (which they lost to Patty and Selma), they started making out with each other.

Bisexual

 * The Cool Moms (except Marge) - They are a group of four moms, all married, and each one has a son about Bart's age. When Marge left the group for the second time, it was revealed that the other three enjoy making out with each other when Marge is not around.
 * Candace - Dated Homer, in a dream that Marge had where she and Homer were separated. On one of their dates, Candace told Homer that she had dated more girls than he had.
 * - Famous billionaire and Mr. Burns' boarding school friend. Is currently and unhappily married to a young woman, but tries very hard to win Smithers in a bet. After he loses, Smithers saves his finances by gaslighting Burns and Nigel then kisses Smithers in gratitude. Al Jean has confirmed on his Twitter that he would consider Nigel as bisexual.

Hinted to be Bisexual

 * Helen Lovejoy - Reverend and Helen Lovejoy dress in Goth costumes as part of a scheme to count cards to make money for the church. Later, Marge visits their house and sees they are still in costume. Rev. Lovejoy implies the costumes help their sex life. From the back we hear Helen Lovejoy say, "Is that a woman's voice I hear? Send her in."
 * Duffman - Slept with Titania, who was competing in a bartending contest that he was judging. However, Bart mentions that Duffman is supposedly in a long-term gay relationship after seeing him dining with Booberella. He is later in a relationship with Julio. It should be noted, however, that there are several different actors portraying Duffman, and not all of them necessarily have the same sexual orientation.
 * The Sea Captain - Apu delivers pornographic magazines to keep the Sea Captain's crew from resorting to situational homosexuality for about ten minutes, at least. However, the Captain is also seen taking pictures of Selma and Patty in the nude to cope with being out at sea.
 * Santa's Little Helper - Intrigued by male dogs at the Springfield Gay Pride Parade. However, he mated with both She's The Fastest and Rosa Barks, both of whom were definitely female as both unions produced puppies.
 * Ralph Wiggum - Declares "I like men now!" after seeing Bart naked on a skateboard. However, Lisa Simpson was his first crush. It should be noted, though, that nothing Ralph says about himself is reliable since his understanding of everything is questionable.
 * Milhouse Van Houten - Noted as having "flamboyantly homosexual tendencies" by Dr. J. Loren Pryor, but has a long-standing crush on Lisa Simpson and has dated other girls.
 * Martin Prince, Jr. - Generally effeminate; accused of being gay by Nelson Muntz and protests, "I'm not anything yet!"; has a male robot boyfriend in the future. On the other hand, he did have an attraction to Princess Kashmir on seeing Bart's photo of her dancing with Homer, even referring to it as being "quite exciting" and calling her a "sexy lady" when he asked Bart who she was. He once had a fantasy about a girl and a boy holding his hands and he was staring at the boy dreamily.
 * Lisa Simpson - In the future, she had relationships with three other girls, two of them at the same time, and eventually married Milhouse. Whether she will enter these relationships in this timeline or not is unknown.
 * Shauna - She invited 200 boys and 7 girls to make out with her over SpringFace.

Transgender

 * Clara Hosenfrauen - was formerly Roy Molloy.
 * Constance Harm - Indicates that she was born male.
 * Brunella Pommelhorst - Took a leave of absence from teaching gym at Springfield Elementary School and said she would return next semester as Mr. Pommelhorst, the new shop teacher, after having a female-to-male gender reassignment surgery. However, she was later seen at the school looking the same as before, so apparently she decided not to go through with the operation.
 * Stanlerina - Transgender male-to-female; cousin of Helen Lovejoy. Helen constantly brags about her (much to Marge's annoyance), evidently to present herself as being accepting of LGBT people. The Simpsons met Stanlerina when Helen was taking her for a hormone treatment.

Hinted to be Transgender

 * Helen Lovejoy - The Parson tells Reverend Timothy Lovejoy that he "remember[s] when [Helen Lovejoy] was Helen Schwartzbaum. In fact, I remember when she was Harold Schwartzbaum." This is highly questionable, however, due to her and Tim having a daughter together, as well as a flashback clearly depicting Helen as a young girl.
 * Waylon Smithers, Jr. - Smithers hinted at possible transgender feelings when Marge was selling prescription medication at a garage sale and he bought bottles of estrogen for "a friend... who's trapped in the body of another friend."
 * Dewey Largo - Sought gender reassignment surgery from Dr. Nick, but because Nick had the surgery files mixed up, Largo ended up getting an operation intended for Moe which made him shorter. Moe, meanwhile, was told "When you wake up, you'll be a woman", indicating that Largo's intended operation was gender reassignment.
 * Francine Simpson - Homer Simpson's history about Francine Simpson implied that she transitioned in 1976.
 * Martin Prince, Jr. - Is shown to have become "Marcia Princess" thirty years in the future; however, this is considered to be non-canon information due to the future setting.