Knotts got his first taste of showbiz in the Army during WWII while serving in the South Pacific Theatre of Operations. More specifically, he was a comedian in a touring G.I. variety show called "Stars and Gripes". After the service, Knotts went to college where he earned a teaching degree but turned down a fellowship, opting to move to NYC to pursue acting. He found work in radio and TV, doing a stint on a soap and on the children's show "Howdy Doody", as Tim Tremble, a nervous friend of Buffalo Bob. Knotts gained some attention with sketch appearances on "The Gary Moore Show" and, from 1956-60, gained further exposure as part of the ensemble of "The Steve Allen Show", a superior NBC comedy variety series. In between TV assignments, Knotts made his Broadway debut in 1955's "No Time for Sergeants", his first collaboration with Griffith. He reprised the role of Manual Dexterity Corporal for TV on CBS's "The US Steel Hour" and the 1958 feature (his film debut). The latter again paired him with Griffith who subsequently hired Knotts to co-star in his sitcom.

Knotts left "The Andy Griffith Show" to pursue a feature career. He had fared well in supporting roles, notably playing a mousy shoe salesman in the Doris Day vehicle "Move Over, Darling" (1963), but his TV success gave him leading man status beginning with "The Incredible Mr. Limpet" (1964). This innocuous family film--a live-action/animation blend about a wimpy bookkeeper and fish-lover who becomes a war hero after magically transforming into a dolphin-- was no great shakes but remains a fond memory to many thirtysomethings who watched TV in their youth. His subsequent films were also low-budget kiddie fodder whose titles tell the tale: "The Ghost and Mr. Chicken" (1966), "The Reluctant Astronaut" (1967) and "The Shakiest Gun in the West" (1968). The latter, a remake of the 1948 Bob Hope vehicle "The Paleface", was one of his better efforts. Knotts' 60s film career concluded with "The Love God?" (1969), helmed by "Sgt. Bilko" creator Nat Hiken, in which he played a take-off on PLAYBOY's Hugh Hefner named Abner Peacock.

After a brief return to TV as the host and star of the comedy-variety series "The Don Knotts Show" (NBC, 1970-71), the 70s found Knotts in more juvenile film fare, sometimes paired with Tim Conway in broad comedies. The duo of TV veterans appeared in six features together (as of 1996) beginning with the Disney Western comedy "The Apple Dumpling Gang" (1975). Knotts had to return to TV to enjoy a more high profile project.

Joining the hit "sexy" sitcom "Three's Company" in 1979 as busybody landlord Ralph Furley, Knotts stayed for five seasons, often clad in a ridiculous leisure suit, leering and bugging out at the amorous hijinks of his youthful tenants. He put his badge back on to reprise the role of Barney Fife, now engaged and running for sheriff, in the hugely popular reunion TV-movie "Return to Mayberry" (NBC, 1986), and the character was revisited once more in 2003's "The Andy Griffith Show Reunion: Back to Mayberry" (NBC, 2003). He and Griffith were subsequently reunited on the latter's NBC courtroom drama series "Matlock". From 1988-92, Knotts played the recurring role of pesky neighbor Les Calhoun, the self-proclaimed "King of Plastic".

Knotts has also appeared in numerous specials throughout his long TV career, often as the star. He has also done stage and voice work. Knotts returned to movies--albeit direct-to-video--as Principal Kokelar in the high school comedy "Big Bully" (1996). He fared much better with his pivotal role as a mysterious TV repairman in "Pleasantville" (1998). Knotts continued to appear often on television, playing himself on former co-star John Ritter's ABC sitcom "8 Simple Rules..." in 2003, as well as on a 2005 episode of the NBC series "Las Vegas." He then lent his quavery vocals to Disney's CGI-animated feature "Chicken Little" (2005) as Mayor Turkey Lurkey, which was released a few months before the actor's death in early 2006 at age 81.