If it's crap ... We'll tell you
Mine is in sitcoms as well and is the tradition of the retarded character. This character says stupid, random, throwaway lines and little else, and it's writing at it's laziest.
Also in the light Sci Fi genre we have the alien hard man stereotype like Worf, Teal'c, Ronon Dex and D'Argo.
Funny, I find the worst cliches of The Big Bang Theory to be the ENTIRE CAST!
Chuck just CANNOT write a single female character that isn't either a girlfriend or a slut. Penny is BOTH.
And gee, we have four intelligent and highly skilled scientists...who somehow have the time to always hit their comic book shop once a week, and sit around playing video games....because, you know, people with brains are automatically required to be 1980s nerd stereotypes. Leonard is the closest thing in the cast to a normal smart guy...and that's just...sad.
The whole show is a titanic FUCK YOU to women of any kind and geeks, nerds or anyone with an IQ over 90...because hey, it's fun to make fun of people that are smart, because you KNOW smarts equal MUTANT FREAK!
Fuck you, Chuck. I hope Charlie Sheen kicks your ass someday AND outlives you.
I don't watch The Big Bang Theory, but a friend of mine once said it was to nerds what Amos and Andy was to black people.
From what I've heard people say, I'd have to agree.
How about " If you're here and I'm here then that means... uh-ohhhhhhh"!!!!! and the classic Plan two dates on the same night at the same Restaurant
ROFL. If only this happened.
I don't think the characters-getting-together-and-then-breaking-them-up cliche is limited to sitcoms. It's the old Moonlighting problem. You base a show around the main characters sexual tension with one another and you can't get them together because you lose that dynamic. So you get them together because you can't keep them apart for 5-6 seasons and then you immediately split them up.
Fringe is a good example of this. Olivia and Peter get together and then something happens; Olivia is switched with Faux-livia, Peter is wiped out of existence, and again just recently they've done something to split them apart as they just got together again. My biggest problem with this cliche is when the sexual tension is not a big part of the show. Fringe has interesting stories without the Olivia-Peter relationship, so why not just get them together and have them figuring out their relationship while all the other interesting stuff is happening.
Another couple of examples would be X-Files and Friends. I personally think it's pretty bad writing when you can't figure out how to use the change in dynamic to your advantage.
A scientist explains something in the plot using basic and easy to understand scientific terms.
"WHOA WHOA, SPEAK ENGLISH DOC."
When sitcoms never go past the whole: set up, punchline, repeat; gag. So... pretty much all sitcoms on CBS except HIMYM.
The love interest
I brought this up in a thread about movie cliches, but it applies to TV as well: The Obvious Mole. This is a character that occurs in a lot of mystery/thriller series who you can easily tell is going to betray the protagonist at some point. What makes them so easy to spot is that early on this character seems to have no reason for being in the series, and yet there they are, just lurking off to the side. They have minimal character development. They barely contribute anything to the plot. They have very little dialogue. Their only reason for being in the series is to shoe in a little bit of conflict by playing the role of a traitor. I was watching Missing a few weeks ago with my family, and I brought this up about a certain character who matches my description to a T. Sure enough, later in the episode, she betrays the CIA.