Allen Kelsey Grammer (born February 21, 1955) is an American actor. He gained fame for his role as the psychiatrist Dr. Frasier Crane on the NBC sitcom Cheers (1984–1993) and its spin-off Frasier (1993–2004, and again from 2023 to 2024). With more than 20 years on air, this is one of the longest-running roles played by a single live-action actor in primetime television history. He has received numerous accolades including a total of six Emmy Awards, three Golden Globe Awards, a Screen Actors Guild Award and a Tony Award.

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 mid-1983, he acted alongside Mandy Patinkin in the original off-Broadway production of Stephen Sondheim's musical Sunday in the Park with George. He has since starred in the leading roles in productions of Sweeney Todd: The Demon Barber of Fleet Street, My Fair Lady, Big Fish, and Finding Neverland.

In film, he is known for his role as Dr. Hank McCoy / Beast in the superhero films X-Men: The Last Stand (2006), X-Men: Days of Future Past (2014) and The Marvels (2023). 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 (1990–present). He took guest roles in the sitcoms 30 Rock (2010–2012), Unbreakable Kimmy Schmidt (2016), and Modern Family (2017). For his performance as the corrupt mayor in the Starz political series Boss (2011–2012), he received a Golden Globe Award for Best Actor – Television Series Drama.

In early 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 mid-2016, Grammer won a Tony Award for Best Musical as producer of a musical revival of The Color Purple. In early 2019, he starred as Don Quixote in a production of Man of La Mancha at the London Coliseum. In late 2023, The Telegraph described Grammer as one of "the finest actors" of his generation. He was awarded a star on the Hollywood Walk of Fame on May 22, 2001.

Allen Kelsey Grammer was born on February 21, 1955 in Saint Thomas, U.S. Virgin Islands. Grammer's mother, Sally Cranmer (1928–2008), was a dancer who performed under the name of Sally Sullivan. His father, Frank Allen Grammer Jr. was a musician who owned a coffee shop, Greer's Place; and owned and edited a magazine, Virgin Islands View. Kelsey had a younger sister, Karen, and four half-siblings from his father's second marriage.

Grammer's personal life has been shaped by many family tragedies. Following his parents' divorce, Grammer was raised in New Jersey by his mother and maternal grandparents, Gordon and Evangeline Cranmer. The family later relocated to Pompano Beach, Florida. When Grammer was twelve years old, his grandfather died of cancer. In 1968, his father was murdered in Saint Thomas during a wave of racial violence following the assassination of Martin Luther King Jr. In 1975, his sister was kidnapped, raped, and murdered in Colorado Springs, Colorado, by spree killer Freddie Glenn. In 1980, his two teenage half-brothers died in a scuba diving accident.

Grammer attended Pine Crest School, a private preparatory school in Fort Lauderdale, Florida. It was there that he first began to sing and perform on stage. Grammer later won a scholarship to study drama at the Juilliard School, where he was a member of Group 6 from 1973 to 1975. However, after his sister's murder, Grammer failed to attend classes and was eventually expelled.

Grammer described himself as "a Caribbean kid", and he enjoys vacationing in the Bahamas, the US Virgin Islands, and British Virgin Islands.