1. 'The Many Loves of Dobie Gillis' (1960)

Just before we met Don Knotts as Barney Fife on The Andy Griffith Show when it premiered in October 1960, Knotts showed up on The Many Loves of Dobie Gillis in an episode that aired that year in July. In "Rock-a-Bye Dobie," Knotts plays the father of Dobie's sweetheart, whom the Gillises suspect may be pregnant, through a sitcom-ish turn of events. Knotts delivers a stammering performance as a pushover dad who sweetly defends young love.

Image: 20th Television

2. 'Here's Lucy' (1973)

If you were a fan of Don Knotts' flamboyant scarves as Ralph Furley on Three's Company, you can likely thank Lucille Ball's wardrobe for inspiring the flourish. In the hilarious 1973 episode "Lucy Goes on Her Last Blind Date," Knotts plays the goofball that Lucy gets set up with. 

3. 'Fantasy Island' (1978)

Knotts was invited to Fantasy Island twice in the late 1970s. Pictured here is his first appearance in the segment "Trouble, My Lovely," where Knotts played a simple desk jockey who decides to play private eye for a weekend (a fanciful plot that reminds us of Knotts' great '60s picture The Ghost and Mr. Chicken). The other episode aired in 1979 and saw Knotts become a casting director for a big Hollywood movie.

Image: Sony Pictures Television

4. 'Three's Company' (1979-1984)

Knotts became a familiar face to a whole new generation of TV viewers when he joined the cast of Three's Company in 1979 as the colorful landlord Ralph Furley. Although Mr. Furley drew from Knotts' treasure trove of comedic faces, Andy Griffith went on record to say he enjoyed Knotts better as Barney Fife (he may be a bit partial). Still Knotts did just as much to make the leisure suited-landlord Ralph Furley his own, even adding a toupee to his character halfway through the fourth season as Knott's own special touch. 

Image: The Program Exchange

5. 'The Love Boat' (1979)

When Don Knotts walked aboard The Love Boat in 1979, he arrived as a shoe salesman, but he instantly became mistaken for a very famous TV star. It was just another example of The Love Boat celebrating the celebrities it packed aboard its ship, and Knotts, of course, was invited back to board again for "Who Killed Maxwell Thorn?" in 1987, waltzing the deck with a sea of classic TV icons like Barbara Billingsley, Tom Bosley, Florence Henderson, Tina Louise and many other stars.

6. 'Newhart' (1990)

Could there be anything better to kick off the 1990s than finding an excuse for Don Knotts to form a group hug with Bob Newhart on air? The moment came in the Newhart episode "Seein' Double," where Knotts plays a character named Iron who comes in at the very end of the episode for a quick cameo. 

7. 'Matlock' (1988-1992)

Of course, the TV reunion fans most wanted to see actually came in 1988 when Don Knotts and Andy Griffith appeared onscreen together for 17 episodes of Matlock. Knotts played Matlock's neighbor Les Calhoun, and the very first time we see Knotts is this adorable moment (practically snagged right from The Andy Griffith Show) when he peeks in the window to see Griffith at his kitchen table.

8. 'Step by Step' (1993)

In a double-nostalgic twist, Knotts appeared on TV for another reunion with a former castmate, this time Suzanne Somers on her post-Three's Company sitcom Step by Step. In the episode "Christmas Story," Knotts plays Deputy Feif, and a recurring joke is to mispronounce "Feef" as "Fife." Between that and his brown uniform, this likely led many fans of The Andy Griffith Show to do a double-take back in 1993.

Image: Warner Bros. Television Distribution

9. 'That '70s Show' (2005)

One of Knotts' most recent TV appearances featured another throwback to one of his classic characters, this time Ralph Furley. In the That '70s Show episode "Stone Cold Crazy," a male character on the show called Fez has a daydream about becoming roommates with a female character, Jackie. What follows is a sequence that parodies Three's Company, complete with a Don Knotts cameo in the imagined credits as "The Landlord."

Image: Carsey-Werner Distribution

See also: Ron Howard confirms nobody could make Andy Griffith laugh like Don Knotts

Just try not to smile when you watch this super-cut of Barney making Andy laugh. Watch now.