Acting
After developing his skills as a stand-up comedian, Reiser had a breakout film role in 1982 when he appeared in Diner, a coming-of-age film directed by Barry Levinson. Reiser's character, Modell, a closet stand-up comedian, effectively brought Reiser's abilities to the attention of Hollywood. He followed this success playing a detective in Beverly Hills Cop (1984), a role he reprised in its sequel Beverly Hills Cop II (1987), and again in Beverly Hills Cop: Axel F. Reiser also appeared in James Cameron's Aliens (1986), in which he played the villainous Carter Burke; and in The Marrying Man (1991) and Bye Bye Love (1995).
Reiser starred as one of two possible fathers of a teenage girl in the TV sitcom My Two Dads (1987–90), and later came to prominence in North America as Paul Buchman in Mad About You (1992–99), a comedy series he co-created, in which Helen Hunt co-starred as his on-screen wife. He was also the co-composer of the show's theme song, "The Final Frontier" (with Don Was), and performed the piano for the theme's recording. Reiser's role in Mad About You earned nominations for an Emmy, a Golden Globe, an American Comedy Award and a Screen Actors Guild Award for him. For the show's final season, Reiser and Hunt received $1 million ($1.9 million today) per episode. After signing onto a Mad About You revival in 2018, it was picked up as a 12-episode limited series by Spectrum Originals in March 2019, which became available for members of Amazon Prime Video as of fall 2020.
In 2001, Reiser played a dramatic role as a man desperate to locate his biological mother, after learning he has a serious illness, in the British TV film My Beautiful Son. In 2002, Reiser made a guest appearance as himself on Larry David's HBO sitcom, Curb Your Enthusiasm. In the TV comedy film Atlanta (2007), Reiser appears as one half of a couple who, after meeting at a funeral, are unable to stay away from each other. In 2010, Reiser collaborated with the singer Julia Fordham to create a CD album titled Unusual Suspects, which includes the song "UnSung Hero", dedicated to American soldiers serving in Afghanistan. The two embarked on an acoustic tour after its release. Reiser also co-wrote the song, "No There There" with Melissa Manchester for her 2015 album, You Gotta Love the Life. Early in his career, Reiser was the opening act for Manchester, who warned him that music audiences can be rough on comedians and that the last comedian that opened for her left the stage in tears. Reiser reflects about this warning and on how he then bombed at the Concord Hotel in the chapter "Don't Worry if They Suck" in I Killed: True Stories of the Road from America's Top Comics (2010), by Ritch Shydner and Mark Schiff.
Reiser scripted and starred in the semi-autobiographical comedy series The Paul Reiser Show, which aired on NBC as a mid-season replacement during the 2010–11 TV season. "This is nice", commented Reiser on the Stephanie Miller radio program, "because you get to sit around and root for other shows to fail." However, due to the lack of lead time and promotion by NBC prior to its debut (as well as poor scheduling), the low-rated show was canceled on April 22, 2011, with only two episodes aired. He co-created (but did not star in) the 2017 dramedy There's... Johnny!, set backstage at The Tonight Show Starring Johnny Carson in 1972. Originally created for Seeso, the seven-episode season was released on Hulu after Seeso's collapse. In recent years Reiser has appeared in films such as Whiplash and TV series such as Red Oaks, Stranger Things and The Boys.
In 2022, Reiser appeared in the third season of The Boys as The Legend, and reprised his role in the fifth season.
In 2024, Reiser will revisit his Aliens character for a new Marvel comic titled Aliens: What If...? which will explore what could have happened if Carter Burke survived the events of Hadley's Hope. The book is co-written by his son, Leon Reiser, with art by Guiu Vilanova.