Allen Kelsey Grammer (born February 21, 1955) is an American actor. He gained fame for his role as psychiatrist Dr. Frasier Crane on the NBC sitcom Cheers (1984–1993) and its spin-off Frasier (1993–2004). At nearly 20 years, this is one of the longest-running roles played by a single live-action actor in U.S. television history. He has received numerous accolades including a total of five Emmy Awards, three Golden Globe Awards, a Screen Actors Guild Award, and a Tony Award. He was awarded a star on the Hollywood Walk of Fame in 2000.

Grammer, having trained as an actor at Juilliard and the Old Globe Theatre, made his professional acting debut as Lennox in the 1981 Broadway revival of Macbeth. The following year, he portrayed Cassio acting opposite Christopher Plummer and James Earl Jones in Othello. In 1983, he acted alongside Mandy Patinkin in the original off-Broadway production of Stephen Sondheim's musical Sunday in the Park with George. He's since starred in the leading roles in productions of both Sweeney Todd: The Demon Barber of Fleet Street and My Fair Lady.

On film, he is known for his role as Dr. Hank McCoy / Beast in the superhero film X-Men: The Last Stand (2006). His other roles include Down Periscope (1996), The Pentagon Wars (1998), and Swing Vote (2008). He is also known for his voice roles in Anastasia (1997), Toy Story 2 (1999), and as Sideshow Bob in The Simpsons. He has appeared in the sitcoms 30 Rock, Modern Family, and Unbreakable Kimmy Schmidt. For his role as the corrupt mayor in the political series Boss (2011–2012), he received a Golden Globe Award for Best Actor – Television Series Drama.

In 2010, Grammer returned to Broadway in the musical revival of La Cage aux Folles, where he received a nomination for the Tony Award for Best Leading Actor in a Musical. In 2016, Grammer won a Tony Award for Best Musical as producer of a musical revival of The Color Purple. In 2019, he starred as Don Quixote in a production of Man of La Mancha at the London Coliseum.