In The Washington Post's obituary of Simon's brother Danny, a television writer, Adam Bernstein wrote that the idea for the play came from his divorce.

"Mr. Simon had moved in with a newly single theatrical agent named Roy Gerber in Hollywood, and they invited friends over one night.

[5]Felix Ungar, a neurotic, neat freak news writer (a photographer in the television series), is thrown out by his wife, and moves in with his friend Oscar Madison, a slovenly sportswriter.

Despite Oscar's problems – careless spending, excessive gambling, a poorly kept house filled with spoiled food – he seems to enjoy life.

Even when he tries to do so in a gentle and constructive way, his corrections and suggestions prove extremely annoying to those around him, eventually breaking up the ritual weekly poker game with friends.

[8] In 1970, the McMaster Shakespearean Players performed The Odd Couple with Martin Short as Felix, Eugene Levy as Oscar, and Dave Thomas as Murray; all three actors would later find fame as cast members of SCTV.

In 1994, a version of the play moved to The Kings Theatre, Glasgow and toured Scotland, starring Gerard Kelly as Felix, Craig Ferguson as Oscar and Kate Anthony as Gwendolyn Pigeon.

In 1996, Klugman and Tony Randall reprised their roles from the TV series for a three-month run at the Theatre Royal in Haymarket, London.

In a 1997 issue of Premiere magazine, Billy Crystal and Robin Williams announced a possible stage revival, in anticipation of success of their film Fathers' Day (1997).

This production ran at the Geffen Playhouse (Los Angeles) from June 2002 to July 21, 2002 with a cast that starred Gregory Jbara (Vinnie), John Larroquette (Oscar), Joe Regalbuto (Felix) and María Conchita Alonso (Ynes) and was directed by Peter Bonerz.

In 2016, Australian comedians Shaun Micallef and Francis Greenslade starred as Felix Ungar and Oscar Madison in a version of the play directed by Peter Houghton.

The Female Odd Couple was based on the same story line and same lead characters, now called Florence Ungar and Olive Madison.

Directed by Gene Saks, responsible for the 1968 film version, the leads were Sally Struthers as Florence (Felix) and Rita Moreno as Olive (Oscar), respectively, with Lewis J. Stadlen and Tony Shalhoub (in his Broadway debut) as the Costazuela brothers.

[17][18] A London production of this version ran at the Apollo Theatre in 2001 and starred Paula Wilcox (Florence) and Jenny Seagrove (Olive).

In 1968, The Odd Couple was made into a highly successful film starring Jack Lemmon as Felix and Walter Matthau reprising his role from the play.

In 1998, Jack Lemmon and Walter Matthau reprised their roles for the film sequel The Odd Couple II, produced by Neil Simon.

Neil Simon originally disapproved of this adaptation, but by the series' final season, he reassessed the show positively to the point of appearing in a cameo role.

Robert Klane was the writer and director, with a cast that included Barbara Barrie as Felix's wife, Penny Marshall as Myrna and Dick Van Patten.

Jack Klugman's real-life throat-cancer surgery was written into the script, when Felix (Tony Randall) stays with Oscar and helps with his rehabilitation.

[23] In the fall of 1975, ABC aired a cartoon version of the play entitled The Oddball Couple, produced by Paramount and DePatie-Freleng Enterprises.

It adds nothing new to the craft of situation comedy, but it does provide employment and a good showcase for talented black actors, who generally don't have an easy time of it on television these days".