I know him from Gilmore Girls; and Supernatural; and A Ring of Endless Light; and Cry_Wolf.
I know him from Miss Guided; and 30 Rock; and Suburgatory; and Grown-ish; and I probably must have seen him on Saturday Night Live; and an episode of Miracle Workers; and surely some other stuff, including voice work (such as the Progressive Box in some Progressive insurance commercials).
I know him best from The Big Bang Theory. But there's also a minor role in Garden State; and The Muppets; and Wish I Was Here. And voice work in an episode of Eureka; and Elf: Buddy's Musical Christmas; and Michael Jackson's Halloween; and Marlon Bundo in an episode of Last Week Tonight. Also various commercials (mainly for Intel).
The first thing I remember him from is Profit. Later I saw a bit of Mysterious Ways, but I mainly know him for Heroes. There was also a recurring role in Agents of SHIELD. And I may have seen him in other stuff that I don't recall.
I know him from The Princess Bride; and Chicago Hope; and Alien Nation; and Dead Like Me; and a minor role in Dick Tracy; and Wish I Was Here. Possibly I've seen him in other stuff, I dunno.
Paxton, Bill (not to be confused with Bill Pullman)
I know him from Weird Science; and Aliens; and True Lies; and Twister; and Traveller; and Titanic; and Thunderbirds; and several episodes of Agents of SHIELD; and Edge of Tomorrow; and possibly some other stuff.
I know him from Supernatural; and Lost; and Revolution; and The Tomorrow People. I may have seen him in some other stuff that I don't remember him from, but I wouldn't mind seeing more of his work.
I know him from Battlestar Galactica; and Dollhouse; and season 9 of Supernatural; and Trick 'r Treat; and The Portal; and I've surely seen him in things I've forgotten about.
I know him from Van Wilder; and How I Met Your Mother; and Sunnyside; and surely some things I've forgotten.
I know him from Beauty and the Beast; and The Adventures of Captain Zoom in Outer Space; and the Hellboy movies; and Bunraku; and Season of the Witch; and Pacific Rim; and Alien Resurrection; and probably various live-action roles (most of which probably involve a bunch of makeup and prosthetics or whatever), but also a fair amount of voice work.
I know him from Lethal Weapon 2; and Goodfellas; and the Home Alone movies; and My Cousin Vinny; and I feel like there must be more than that, but maybe not.
I know him best from Star Trek: Voyager; but there's also Benson; and the short film 9mm of Love; and an episode of Deadbeat; and surely various things I'm forgetting.
I know him from Star Trek: Voyager; and China Beach; and The Wonder Years; and Gremlins 2; and Morganville: The Series; and a couple episodes of The Orville; and The Candidate; and surely things I've forgotten.
Pierce, David Hyde
I know him from The Powers That Be (though I don't remember that well); and Frasier; and When We Rise; and some voice work.
First and foremost I know him for The X-Files, of course. There was also Tarzan; several eps of Supernatural; and voice work on The Batman. Probably some guest roles in other things that I don't really remember.
I know him from the rebooted Star Trek movies; and Into the Woods; and voice work in Rise of the Guardians.
I know him from The Red Green Show; and Due South; and possibly some other stuff.
I know him from Thelma & Louise; and Cool World; and Interview with the Vampire; and 12 Monkeys; and Mr. & Mrs. Smith; and Babel; and voice work in Megamind.
I know him from Flatliners; and The Three Musketeers; and Bicentennial Man; and Don't Say a Word; and Pieces of April; and Casanova; and probably things I've forgotten. Also voice work in Legends of Oz: Dorothy's Return; and Wonder Woman.
I know him from Fantastic Voyage; and Escape to Witch Mountain; and Halloween; and Escape from New York; and Phenomena; and an episode of The Ray Bradbury Theater. And doubtless he's done lots of other things I'd like to see.
I know him from The Sound of Music; and Star Trek VI: The Undiscovered Country; and Dracula 2000; and The Imaginarium of Doctor Parnassus; and Somewhere in Time; and 12 Monkeys; and A Beautiful Mind. He voiced Charles Muntz in Up; and 1 in 9; and Dr. West in Howard Lovecraft and the Frozen Kingdom; and I've probably seen or heard him in other stuff I don't remember. Plus he's done a ton of other things I've never seen, some of which I really should, someday.
I know him from a recurring role on The O.C.; and Guardians of the Galaxy; and Jurassic World; and some voice work, most notably in The Lego Movie.
I know him for narrating Tim Burton's short film Vincent; and a small role in Edward Scissorhands. I had a DVD one time with three of his movies, House on Haunted Hill, The Last Man On Earth, and The Bat. Didn't particularly enjoy any of them, really. Oh, and there was a cameo in one of those Beach movies. And he did a voiceover on Michael Jackson's "Thriller." And he voiced Ratigan in The Great Mouse Detective. I dunno if I've seen or heard him in anything else, but I'd like to.
Prinze Jr., Freddie
I know him from I Know What You Did Last Summer (and its sequel); and She's All That; and Wing Commander; and Scooby-Doo (and its sequel); and voice work in Kim Possible: A Sitch in Time; and Star Wars Rebels.
Pullman, Bill (not to be confused with Bill Paxton)
I know him from Spaceballs; and A League of Their Own; and The Last Seduction; and Casper; and Independence Day; and Phoebe in Wonderland; and Torchwood (season 4); and 1600 Penn; and The Grudge; and Newsies; and he voiced Captain Korso in Titan A.E.