Stephen Hawking has been in a familiar face in many Sci-Fi shows.

Star Trek Next Generation:
http://www.youtube.com/watch?v=5O31qRH3O6c
http://en.wikipedia.org/wiki/Descent_%28Star_Trek:_The_Next_Generat...
The episode is called Descent
Appeared as himself
- The Culture Show. (Simpsons special)
- Alien Planet. (Discovery Channel special)
- I Love the World . (Discovery Channel commercial)
- Late Night with Conan O'Brien (Episode 1752).[1] He was in a skit in which he made a phone call to guest Jim Carrey.
- Masters of Science Fiction. A Science Fiction anthology series which is hosted by Hawking's (off screen) voice.[2]
- Red Dwarf. Hawking appeared in a special programme about the popular British science fiction series. He praised its creators for their witty use of (pseudo) scientific theories and said he enjoyed watching the show.
- TV Offal. Hawking appeared with host Victor Lewis-Smith in the pre-titles sequences of this show.
- Star Trek: The Next Generation.
- At the beginning of the Season 6 cliffhanger, "Descent, Part 1", Data is seen playing poker with holographic depictions of Stephen Hawking, Sir Isaac Newton, and Albert Einstein. Hawking portrayed his own hologram for this episode, making him the only guest in any Star Trek series to play himself. When taking a tour of the set, he paused at the Warp core, smiled, and said, "I'm working on that." During the tour, Hawking requested, and was allowed, to sit in the captain's chair of the Enterprise-D.
- Brent Spiner (Data) reportedly quipped, in an obviously tongue-in-cheek manner, that Hawking's cameo was "the most notable moment in television history since Albert Einstein guest-starred on Gunsmoke".[3]
- Also, in the 1994 series finale, "All Good Things...", in an alternate future, Data has assumed the Lucasian professorship at Cambridge, the post that Hawking held till September 2009.
- The 11th Hour. In this film about the effects of human activity on the environment Hawking gave explanations of these effects.
- Genius of Britain. Hawking presented the links for a five-part 2010 Channel 4 series profiling British scientists
- Futurama. Hawking has made several guest appearances in Futurama.
- In "Anthology of Interest I" Hawking appears as a member of the Vice Presidential Action Rangers, who guard the space-time continuum. Along with Hawking at the end of the twentieth century they include Al Gore, Nichelle Nichols, Gary Gygax, and their summer intern Deep Blue. He first appears as a customer at the pizzeria where Fry mistakenly believes him to have invented gravity for which Hawking accepts credit ("Yeah, sure. Why not?"). After learning of Fry's inter-dimensional experience, he arranges for him to be kidnapped by the VPAR.
- In the film The Beast with a Billion Backs, Hawking appears as his own head in a jar leading a scientific convention organized to study and discuss a tear in the universe. He says that despite writing a book about it, he has no idea what it is. After stunning Professor Farnsworth and Professor Wernstrom with beams from his eyes, he is surprised, remarking, "I didn't know I could do that" . Hawking provided his "own" voice for this appearance, and is characterised the same way as in The Simpsons.
- Hawking will appear in the video game segment of the last episode of Futurama's sixth season, "Reincarnation".
- The Simpsons. Made several guest appearances on the long-running prime-time cartoon:
- In "They Saved Lisa's Brain", Hawking saves Lisa from the power-hungry Springfield chapter of Mensa in a special wheelchair, complete with an Inspector Gadget–style retractable helicopter attachment and a spring-loaded boxing glove. In the episode, Homer says to Lisa "Did you have fun with your robot buddy?". Earlier, Homer mistakenly calls Hawking Larry Flynt ("Larry Flynt is right! You guys stink!"). After the events involving Lisa, Homer invites Hawking to Moe's Tavern for a beer. Hawking accepts, commenting, "That's the smartest thing I've heard all day." In the bar, Hawking tells Homer "Your theory of a donut shaped universe intrigues me, Homer. I may have to steal it". When it comes time to pay for the beer and Moe asks who is paying Homer pretends to be Hawking saying in his robot voice "I am". Hawking responds with "I didn't say that". Homer replies "Yes I did." At this point Hawking hits him with his wheelchair's boxing glove, to which Homer, still imitating Hawking's voice, says "D'oh!"
- In "Treehouse of Horror VI", Homer makes a reference to Stephen Hawking when he is transported to a three-dimensional zone, and moans "There's so much I don't know about astrophysics. I wish I read that book by that wheelchair guy."
- Hawking is seen in a line of people about to board a space ship to Mars in "Life's A Glitch, Then You Die", a segment of "Treehouse of Horror X", in which the Earth is doomed by the millennium bug.
- Hawking is also referenced in the episode The Great Louse Detective where Sideshow Bob is temporarily released to help Homer find a person who is trying to kill him. Homer lists Stephen Hawking as someone who would want to kill him.
- During the British Comedy Awards 2004, Hawking was presented with a one-off toy version of himself in Simpson form by Matt Groening, complete with boxing glove. Hawking presented Groening with a lifetime achievement award.
- In the Season 16 episode "Don't Fear the Roofer", he is a friend of Lenny and the owner of the Little Caesars restaurant down the block from Moe's Tavern. Prof. Hawking shows up to explain that Bart couldn't see Homer's new friend Ray (guest voice Ray Romano) during one scene because there was a black hole between Homer and Bart, thus drawing away the light coming from Ray to render him essentially invisible to Bart, thus enabling Homer to prove his sanity after being institutionalized.
- In the Season 18 episode "Stop or My Dog Will Shoot", the family dog encounters Hawking in a corn maze while searching for a lost Homer. Hawking says "This maze is too hard for me," and then flies off in the helicopter attachment.
- In the Season 22 episode, "Elementary School Musical (The Simpsons)", Hawking raps with Flight of the Conchords for Lisa.
Do you have a favorite show that he appeared in?
My personal favorite is the Star Trek Next Generation episode Descent. (see above for details).
Thanks to Ruth Anthony-Gardner for giving me this discussion idea.