Daniel Tosh to me is the smart ass kid sneaking into country clubs in Taco Bell commercials.
And every role Philip Seymour Hoffman had was always Scotty from Boogie Nights all grown up.
Jeannie Bueller was played by Jennifer “Strong Nose and Curly Hair” Grey, not Jennifer “Strong Nose and Straight Hair” Aniston.
To me David Duchovny was Jake Winters on The Red Shoe Diaries until he was Fox Mulder on The X Files. Then he became Hank Moody. It says a lot about Duchovny as an actor that I never saw Mulder when I watched Californication.
Hank Azaria was the dog walker on Mad About You, before he started voicing for The Simpsons
Morgan Freeman will always be Easy Reader.
Wrong.
Well, OK, right but also wrong.
In the movie (“Ferris Bueller’s Day Off,”) Jeannie was indeed played by Jennifer Grey, the daughter of Broadway great Joel Grey. But in the short-lived TV series “Ferris Bueller,” Jeannie is played by Jennifer Aniston.
Interestingly, in the universe of the TV series, Ferris is a real person upon whom the movie “Ferris Bueller’s Day Off,” was loosely based. TV-Ferris takes a chainsaw to a cardboard cutout of Matthew Broderick as Movie-Ferris to express his primacy as the real Ferris.
Also interesting, Grey wasn’t the only daughter of fame cast in the franchise. Ami Dolenz, daughter of Mickey Dolenz of “The Monkees,” played Ferris’ girlfriend Sloan in the TV series.
As will I. Additionally, from the same movie, Amanda Bearse will always be his girlfriend, instead of Marcy from Married With Children.
Funny, somewhat related story…my Mother used to say, “oh he’ll always be that old west actor to me…” whenever Ronald Reagan was giving his State of the Union address. 
Wow, I had no idea. And when I say “no idea,” I mean I had no idea there even was a TV series. I learned something new today, Bricker. Thanks!
He’s “Roseanne”'s supervisor, Booker, from the early days.
Jennifer Aniston will always be the groupie who locked herself, with Julie Brown, in a trunk to go on tour with (I think) Aerosmith on “The Edge” (Fox, 1992). Later in the episode they were talking skeletons.
Ferris Bueller got its butt kicked by “Parker Lewis Can’t Lose” on Fox.
I remember him first from MTV’s Remote Control
To me, he was Jessel from the 1967 episode “The Superlative Seven” of The Avengers.
I should’ve known him from the anthology movie Dr. Terror’s House of Horrors from 1965, which I saw, but I guess he didn’t make that deep an impression in that.
To me, William Daniels isn’t Dr. Mark Craig from St. Elsewhere or the Voice of K.I.T.T. from Knight Rider, or even John Adams from 1776 (I saw him onstage in the original Broadway run) or Sam Adams or John Quincy Adams (he had the entire Adams family sewn up). Nor Dustin Hoffman’s father in The Graduate. Or Wynn Quantrill of Seaside Heights, New Jersey in The President’s Analyst (where Seaside Heights didn’t look anything like the way it really does).
No, to me, he was always Carter Nash, alter ego to spoof superhero Captain Nice in the pretty much forgotten 1967 sitcom Captain Nice from the folks who gave us Get Smart!
It came and went pretty quickly. 15-year-old me thought it was the funniest thing on television. Adult me is afraid to go back and watch.
Jonathan Frakes (ST:TNG) had a recurring role in *The Waltons, *back in the '70s.
Bob Denver: Far Out Space Nuts
Kyle MacLachlan: Dune, The Hidden
Sid Haig: Jason of Star Command
Jonathan Harris: Space Academy
Jennifer Aniston: the “black-haired beauty” from Bob Segar’s “Night Moves” video.
Courtney Cox: the girl from Bruce Springsteen’s “Dancing in the Dark” video.
I thought that was Daphne Zuniga?
Michael Richards - Translyvannia 6-500
George Clooney - The Facts of Life 
John Hurt – Richard Rich in the movie A Man for All Seasons. He had hair!
Leslie Neilsen – Commander J. J. Adams (the proto-Captain Kirk) in Forbidden Planet
In 1967 I watched a televised version of Maxwell Anderson’s play The Star Wagon. The lead actors were Orson Bean (one of my favorite actors) and Dustin Hoffman (who was, to me, totally unknown). Hoffman just blew me away. His performance as a slow-witted man named Hanus Wicks was one of the finest jobs of acting I have ever seen. I made a note of his name and hoped to see him again. Much to my delight, I did see him again, not long after, in The Graduate and Midnight Cowboy and on and on…
It has been 48 years since I saw The Star Wagon, yet I think of Hanus Wicks every time I see Dustin Hoffman. I just discovered that someone has posted The Star Wagon on YouTube, and I think I’ll see whether 67-year-old me likes this play as much as 19-year-old me did.
Checking Wikipedia, I stand corrected.
For me, Dustin Hoffman will always be Little Big Man. And Faye Dunaway will always be the preacher’s wife.
I can’t be the only one with the following.
Daniel Dae Kim is Gavin from Angel.
He later went on to be Jin from Lost and I guess he is on Hawaii 5-0 now.
Still, he was Gavin to me.