Frasier Crane

Frasier Crane is a psychiatrist in the TV series Cheers and Fraiser, played by Kelsey Grammer.

History
Homer, while looking for a new bar to hang out in after being kicked out of Moe's, briefly stops at Cheers. He sees the regulars and staff working there, including Frasier, but is scared out by Normie's alcoholism and finds another bar.

Bart and Homer watched an episode of Fraiser, where he asked Niles why he permitted dad to intimidate him.

Behind the Laughter
"Brother from Another Series" frequently refers to Frasier, as Kelsey Grammar and David Hyde Pierce both play brothers Sideshow Bob and Cecil, respectively. Both pairs of brothers share similar dynamics.

Frasier has been seen in person by Homer, and has also referred to as a fictitious person by Marge. Consequently, his status as a character in the context of The Simpsons is unknown.