He originated the voices of many familiar Hanna-Barbera characters, including: Yogi Bear, Huckleberry Hound, Snagglepuss, Quick Draw McGraw and Baba Looey, Augie Doggie, Loopy De Loop, Wally Gator, Snooper and Blabber, Dixie and Mr. Jinks, Hokey Wolf, Lippy the Lion, Elroy Jetson, Lambsy, Peter Potamus, The Funky Phantom and Hair Bear.

[4][5] In 1935, Butler began performing as an impressionist, entering multiple amateur contests and winning most of them—not with the intention of showing his talent, but as a personal challenge to overcome his shyness.

[5] Throughout the late 1940s and mid-1950s, Butler had roles in many Avery-directed cartoons: the Fox in Out-Foxed, the narrator/cat in The Cuckoo Clock, the Cobbler in The Peachy Cobbler, Mr. Theeves and Spike (one line) in Droopy's Double Trouble, Mysto the Magician in Magical Maestro, John the Cab and John the B-29 Bomber in One Cab's Family and Little Johnny Jet, and Charlie in The Legend of Rockabye Point.

[5] Beginning with The Three Little Pups, Butler provided the voice for a nameless wolf that spoke in a Southern accent and whistled all the time (the tune was Henry C. Work's "Kingdom Coming").

[5][7] In 1949, Butler landed a role in a televised puppet show created by former Warner Bros. Cartoons animation director Bob Clampett called Time for Beany.

[10] In Freberg's "Green Chri$tma$" in 1958, a scathing indictment of the over-commercialization of the holiday, Butler soberly hoped instead that we'd remember "whose birthday we're celebrating".

[8] In 1957, when MGM had closed their animation unit, producers William Hanna and Joseph Barbera quickly formed their own company, and Butler and Don Messick were on hand to provide voices.

The breakfast cereal mascot Cap'n Crunch became an icon of sorts on Saturday morning TV through many commercials produced by Jay Ward.

In Wacky Races, Butler provided the voices for a number of the racers, Rock Slag, Big Gruesome, the Red Max, Sgt.

Along with Stan Freberg, Paul Frees and June Foray, Butler also provided voices for children's records featuring recreations of several successful Disney cartoons and films.

Yogi Bear began as an Art Carney impression; Butler had done a similar voice in several of Robert McKimson's films at Warner Brothers, and on Stan Freberg's comedy record "The Honey-Earthers".

Huckleberry Hound was inspired by a North Carolina neighbor of Butler's wife's family; he previously used the voice for Tex Avery's laid-back wolf and Walter Lantz's Smedley.

In 1975, Butler began an acting workshop which spawned such talents as Nancy Cartwright, Corey Burton, Joe Bevilacqua, Bill Farmer, Pat Parris, Tony Pope, Linda Gary, Bob Bergen, Greg Berg,[13] Greg Burson, Mona Marshall, Brian Cummings,[14] Sherry Lynn, Joey Camen, Keith Scott, Sonny Melendrez, Charles Howerton, Hal Rayle, and writer Earl Kress.

[18] Myrtis Mayfield Martin Butler (born January 13, 1917, Stanly County, North Carolina) died on November 15, 2018, in Beverly Hills, California at the age of 101.

[22] A new book of cartoon scripts written by Butler and Joe Bevilacqua, Uncle Dunkle and Donnie: Fractured Fables, was scheduled for publication in the fall of 2009.

Butler also trained Hal Rayle, who ultimately determined that his best-known character of Doyle Cleverlobe from Galaxy High School should sound like "Elroy Jetson after he finished puberty".