Wikisimpsons - The Simpsons Wiki
During the 1960s, while still living in India, Apu spent some time as a student of the Maharishi Mahesh Yogi, in which capacity he became a friend of Paul McCartney and Linda McCartney. Apu's friendship with the McCartneys caused him to be referred to by some (mainly himself) as "The Fifth Beatle". They visited Apu in Springfield around the time he became naturalized. He says that he graduated from Calcutta Technical Uuniversity, where he was the top of his class of 7 million and got a scholarship in the United States. In the United States he got a doctorate in computer science by designing the world's first tic-tac-toe program that only the top human players could beat (which Bart Simpson promptly broke). He then took a job at the Kwik-E-Mart to pay back his student loans.
During the early 1980s Apu was a member of the barbershop quartet called The Be Sharps, which also consisted of Homer Simpson, Barney Gumble, and Seymour Skinner. Upon the advice of Nigel, the band's manager, Apu took the stage name "Apu du Beaumarche" (a pun, as "du beau marché" means "of the beautiful market" in French) and denied that he was actually Hindu.
Apu and Manjula were wed through an arranged marriage. Despite trying to wriggle out of the arrangement at first, Apu was won over soon after meeting Manjula and the two actually did fall in love. Later, Manjula gave birth to the amazing number of eight children after receiving a larger-than-recommended dose of fertility drugs. Apu and Manjula have a mostly happy marriage, despite understandable marital problems caused by Apu's workaholic nature (he seems to be at his post around the clock), the strain of caring for eight children, and two instances of infidelity by Apu. He and his family are devotees of the Hindu gods Shiva, Ganesha, and Vishnu. At Apu's wedding, Homer, in a misguided attempt to play on the bride and groom's families' fear of the gods, arrived dressed as the Hindu god Ganesh. The impersonation was seen through by one of Apu's relatives and failed miserably. Before his marriage, Apu became known as the leading ladies' man in Springfield, because he holds a Ph.D. and runs his own business. He also admitted, "I'm not much of a talker, but I love to listen. I also like to design and build furniture and then to have a discussion about where it could be placed in a room", which made the single women of Springfield go crazy for him. Despite his hectic marriage and home life however, his first love is still to work in the Kwik-E-Mart, sometimes taking shifts long enough to send him into sleep deprived hallucinations in which he thinks he is "...a humming bird of some kind." Also after Apu had an affair with Annette, the squishy lady, Manjula made him legally change his name to Slime Q Slimedog. He is revealed to have slept with Selma Bouvier.
In addition to being Brahmins, Apu and Manjula appear to be Tamil because of their last names and especially dark complexions and Apu means loving child in Tamil; however, Apu has also been shown to be Bengali. However, Manjula speaks Hindi (interpreted as "baby talk" by Marge), to Maggie, as opposed to Tamil or Bengali, further complicating the matter. Still, Apu's parents very strongly appear to be Tamil. Apu has a cousin named Kavi, who lives in Bangalore, which is part of Karnataka, South India; this would suggest that they are indeed Tamil of Bangalore residence.
 Immigrant status
Apu is a naturalized U.S. citizen and holds a Ph.D. in computer science. He graduated first in his class of seven million at the Calcutta Institute of Technology, going on to earn his doctorate at the Springfield Heights Institute of Technology. His doctoral dissertation was the world's first computer program to play perfect tic-tac-toe (Bart Simpson ruined it years later by plucking a random punch card out of the box along with several others). Apu began working at the Kwik-E-Mart during his college years to help pay off his student loans.
Sanjay, Apu's brother, helps him run the Kwik-E-Mart. Sanjay's daughter (and Apu's niece) is Pahusacheta. Sanjay's son is Jamshed. They all share the Nahasapeemapetilon surname. Apu has another younger brother. When Apu's and Manjula's parents were first arranging their marriage, Apu was shown as the oldest of three on a chart. Apu also has a cousin living in India named Kavi, who helped Homer while he was in India. He works for many American companies taking service calls and can speak with American, Western, and Jamaican accents. This episode, seeing that it takes place in Bangalore, strengthens the theory that Apu is South Indian.
 Video games
Apu is the only non-Simpson family playable character in the video game The Simpsons: Hit & Run, and his standard vehicle is a yellow version of his Pontiac Firebird called "Longhorn". He is in the fifth level which is downtown Springfield at night. He appears walking around Springfield in The Simpsons Game but is a non-playable character. He is also a driver and passenger in The Simpsons Road Rage.
 The Simpsons: Tapped Out
 All-American Apu
Although he did not appear fully in person in The Simpson's sister show, Futurama, his head could be seen in the head museum in "Space Pilot 3000" and "Bender's Big Score".
 Behind the Laughter
As revealed in the season 1 commentary for "The Telltale Head", originally the Simpson staff was not going to make Apu ethnic until they heard Hank Azaria's voice for the character. The staff thought that was hilarious and made him Indian.