While his character on Frasier, Martin "Marty" Crane, is a gruff retired police officer with a distinct American accent, Mahoney himself was English.
He also famously appeared on The Simpsons alongside his Frasier co-stars, Kelsey Grammer and Hyde Pierce, playing Robert Terwilliger, Sr. - the father of Sideshow Bob (played by Grammer) and Cecil Terwilliger (Hyde Pierce).
The character actor was born in England, but moved to the United States at the age of 19 to teach English at a college in IL, according to Variety.
Mahoney had an eventful life even before beginning his acting career, however.
CT forecasts have snow, sleet, rain and lots of 'ifs'
Southeastern Massachusetts will see a burst of snow, resulting in no more than an inch of snow accumulated. That difference in pressure will bring brisk winds with gusts of 20-25 miles per hour here on Thursday .
Mahoney got his acting start in Chicago relatively lately, when he was 40 in the late 1970s, after fellow actors John Malkovich and Gary Sinise invited him to join the then-nascent Steppenwolf, according to the Chicago Tribune.
He became a mainstay of the Steppenwolf Theatre Company in Chicago, winning a Tony Award in 1986 for his performance in John Guare's The House of Blue Leaves. He returned to Broadway in 2007 in a revival of Prelude to a Kiss.
He won a SAG Award and received two Emmy and two Golden Globe nominations for his work on 'Frasier'.
In movies, Mahoney earned recognition in Tin Men in 1987 alongside Richard Dreyfuss. He was also in the popular films Say Anything and Reality Bites. More recently, he had a recurring role as Betty White's love interest in Hot in Cleveland. He lent his voice to such animated films as Antz (1998), The Iron Giant (1999) and Atlantis: The Lost Empire (2001).
Mahoney's last TV appearance was in Foyle's War in 2015, where he played Andrew Del Mar. Remember him well." Wendie Malick, whose character Ronee married Martin in the sitcom's final episode, posted a picture of herself and John on set, and tweeted: "John Mahoney was not only a brilliant actor on stage & screen, but a flawless gentleman.