Hugo Weaving will always be Agent Smith. The recent Transformers movie has him at the front of my mind.
Seconded. Seeing Hugo Weaving play what’s-his-face in LoTR (see, I don’t even remember the poor guy’s name) made me think, “Hey, Smith likes to play MMOs when he’s not chasing down hackers!” 
Marisa Tomei - I have seen her in many movies, and she had good roles in The Slums of Beverly Hills or In The Bedroom, but her young (auto mechanic!?!) character in My Cousin Vinny is still the standout.
Sigourney Weaver will always be Ripley.
And Melanie Griffith will always be…Melanie Griffith. No role sticks to her because she’s not much of an actress.
The cast of Gilligan’s Island is always…the cast of Gilligan’s Island.
Gilligan, the Skipper too
The millionaire and his wife.
The movie star
The Professor and Mary Ann
“Whoa. Déjà vu.”
Nope. Dana in Ghostbusters
Sean Connery as 007. He was also the best 007.
Anthony Perkins as Norman Bates.
Andy Griffith as Sheriff Taylor.
Dear Law & Order,
Quit trying to convince me that Angela from Who’s the Boss is a judge. Really. Please. Just stop.
Sincerely,
neutron star
Men? Men are weak! I hate the smell of men!
The gimmie, William Shatner = James Tiberius Kirk. He has done tons of other stuff I will never let it go.
Edward Norton in fight club, I love Death to Smoochy for some bizzare reason, but he will always be Tyler Durden.