He was also a regular on GOMER PYLE which is in the Mayberry-verse.
A few years ago A&E put out A Nero Wolfe Mystery, and turned a 15 or so of the Nero Wolfe books into tv shows. The cast was interesting, as there were a few recurring characters(Nero, Archie, Fritz, Cramer, etc), but the rest of the characters would change from episode to episode. Rather than do what L&O does, they used the same cast members. Obviously the main characters, Nero, Archie, and friends, would be the same actors, but the rest of the cast would be playing different roles every episode, so the murderer one week would be a concerned citizen or have a bit part the next. It was quite impressive to see how they could fill completely different roles.
That sounds really cool. Was it confusing for the audience? I imagine it would be disconcerting if you just watched in the middle and had no idea what was going on.
Supernatural does this fairly often with one-time roles, though they usually space out the appearances of the actors enough to avoid immediate recognition. Some examples of the actors, the episode they were in, and their character names:
**Anita Brown **
Wishful Thinking (2008) Hope Lynn Casey
Skin (2005) Lindsay
Christine Chatelain
Changing Channels (2009) Dr. Ellen Piccolo
Dead Man’s Blood (2006) Jenny
Keegan Connor Tracy
The Monster at the End of This Book (2009) Sera Siege
The Usual Suspects (2006) Karen Giles
There’s another interesting one. Spike has a background story in which he wrote “bloody awful” poetry. He loved Cecily, played by Kali Rocha, but she despised him. Kali Rocha later played the demon Halfrek, who was a friend of Spike. Fans have speculated that they might be the same person. Joss Wheedon had not intended such when she was cast, but did later consider this as a possible storyline.
Ted McGinley played Norman Jablonski in the “It’s a Wonderful Life” episode of Married With Children, before joining the show as Jefferson Darcy the next season.
As I show my age, the thing that stands out to me about her characters is “Jenny Piccolo” - Joanie’s slutty best friend on “Happy Days” . . .
One of the few unseen characters to later become not only seen but a semi-regular (Cathy Silvers [da. of Phil, who made a cameo as her father- I’m old too;)]).
Doctor Who again: I can’t believe I forgot Freema Agyeman. She first appeared on the new show as a Torchwood employee/redshirt in “Army of Ghosts”. When she later came on as companion Martha Jones, the writers carefully gave her a line mentioning her “cousin” who disappeared in the Battle of Canary Wharf.
I just saw this one last night. He played a character called “The Mole” that tried to escape through the sewers but Harris and Wojo pursued and caught him.
I offer an obscure one that I just caught. On the show Star Trek TNG, the actor David Tristan Birkin plays Picard’s nephew in one episode and plays a young version of Picard himself in another. Birkin has a distinctive English accent which makes him stand out (especially for someone playing a French youth).
James Jordan played a 3-episode recurring character in season 2 of Veronica Mars, then returned in the next season as a major character.
::snaps fingers::
Krycek, no h. And he’s not alone, either.
Terry O’Quinn played:
Lt. Brian Tillman in “Aubrey”
Darius Michaud in X-Files: Fight The Future
The Shadow Man in “Trust No 1”
I’m pretty sure there are other actors who played muliple roles on The X-Files, but I can’t recall them now.
I had no idea Vaughn Armstrong was on so many incarnations of ST. Wow!
These actors each played two roles in ST:TOS:
And this actress played two roles in TOS, and one in TNG:
Brent Spiner, of course, played Data, Lore, B4 and Dr. Soong (all variations on a theme, if you will). And Mark Lenard, in addition to playing the Romulan commander and Amb. Sarek, also played the Klingon captain at the beginning of ST:TMP.
Michelle Forbes didn’t play another Starfleet ensign before she played Ens. Ro Laren; she played the daughter of an alien scientist (David Ogden Stiers) in the episode “Half a Life.”
All of the DS9 cast played alternative characters in the episodes where Sisko thought he was an sf writer in the Fifties, and in the James Bond holosuite spoof.
We watched the Special Features on a DVD set of 24, and it seems it’s all the same bad guys getting killed over and over again. The faceless minions, not the main evildoer. 
It wasn’t that confusing*, because the actors were really versatile. It did mean Kari Matchett had to play two different characters in a two-part episode. Normally her roles were episode-specific, but she also had a recurring part as Archie’s gal Lily Rowan. In “Death of a Doxy” she had an episode-specific role and appeared as Lily both. Wikipedia says that Nicky Guadagni played two non-recurring characters in “The Silent Speaker”- I’d forgotten about that.
*I occasionally had trouble remembering if one actor was playing the same character as last time or not, due to how the characters were written and costumed, Julian Richings’ distinctive face, and the fact that I wasn’t paying perfect attention at the time.
In addition, Brian Thompson played Luke in Season 1, and The Judge in Season 2.
Jeff Kober played the psycho vampire hunting Buffy (drained of her powers) in Season 3, and later on the magic “drug” pusher in Season 6.
In one of the earliest episodes of Upstairs, Downstairs, James Bellamy brings home a friend named Billy Watson to meet his sister. Billy is played by John Quayle, who would reappear in several episodes in later seasons as James 's best friend, Bunny Newbury. Even though he goes by another name in this first appearance, I prefer to think of him as Bunny here.
On the Nero Wolfe mysteries. The actor who would play Lon Cohen first shows up in the pilot movie, The Golden Spiders, as Saul Panzer (causing some confusion for me). The recurring actors in the series were rather fun; you’d see the pop-eyed guy or the Bette Midler-y woman again and think “Weren’t you murdered last week?”
Another reappearing pair of actors along similar lines occurred to me later yesterday. In the very first episode of Midsommer Murders, “Killings in Badger’s Drift,” Elizabeth Spriggs and Richard Cant appear as Mrs. Rainbird and her son, and have their throats cut during the course of the show.
So, imagine my surprise when they both show up again in another Midsommer Murder about ten years later. “Weren’t you two brutally murdered?” I said out loud.
Things took an even more bizarre turn when Insp. Tom Barnaby, on seeing the pair at a village fete, said pretty much the same thing.
It turns out that they were not the murdered mother and son returned from the dead, but their twin sister and identical cousin (like Patty Duke and Kathy).
I just caught an early episode of Everybody loves Raymond where Kevin James played a couch named Kevin.
Later his King of Queens character Doug Heffernan would make several appearanes on Ray’s show.