Yes, they re-used footage shot back in the '70s by Richard Donner, but Superman Returns was not a prequel. I can see where that might count as the sequel, I guess.
Charlie Chaplin? 
James Dean (unsure of his TV career, I don’t recognize any of what’s listed)
I was thinking of Robin Williams, but he had two Night at the Museum movies. Can’t think of any sequels where he was top billed, tho…
Jennifer Connelly - I don’t know for sure, not being familiar with some of the titles. This is a fun game!
Kung Fu Panda II
Nicole Kidman qualifies, I think. Too bad The Golden Compass didn’t do better business.
Batman Forever, I think.
Right, but she wasn’t reprising a role. Similar to RealityChuck’s mention upthread of Helen Mirren in National Treasure 2.
Gotcha, missed that qualification in the OP.
Clive Owen,
and his Children of Men co-star Julianne Moore (though she played a new character in The Lost World, and she subbed for Jodie Foster as Clarice Starling in Hannibal, she didn’t reprise either of those roles in subsequent movies),
and her The Kids Are All Right co-star Annette Bening.
Kate Winslet,
and her *Titanic *co-star Leonardo DiCaprio,
and his Gangs of New York co-star Daniel Day Lewis.
Didn’t Disney also use his voice in a direct-to-video Aladdin sequel (without his permission)?
Well, then, does The Godfather & The Godfather Part II count?:rolleyes:
It would, if Brando was actually in Godfather Part II. 
I can in specifically to mention him. He consopicuously avvoided the tremors sequels and The Hollow Man sequel.*
*his character being dead didn’t keep Yul Brynner out of Futureworld. Or Jack Palance out of the second City Slickers movie.
I went to IMDB to see if Liam Neeson qualified, and had the misfortune of discovering there’s a sequel to the Clash of the Titans remake in production…
Even without that he might be out, as he voices Aslan in multiple Narnia movies.
Set to come out the same year as his upcoming credit in DARK KNIGHT RISES.
Even before that, wasn’t it his voice as Qui-Gon Jinn in ATTACK OF THE CLONES?
Was Gary Oldman ever in a sequel before The Dark Knight?
I only ask because someone took who I was going to say (Daniel Day-Lewis,) so I figured he’s good ‘runner-up’ if we pretend it’s 2007.
Well, X-men: First Class, but it is true that it is a prequel and he didn’t reprise his role from an earlier movie.
Qui-Gon talked in Attack of the Clones?
Right after Anakin’s mom dies and the chosen one starts getting ready to hack a bunch of people into pieces, you can hear something like unto a disembodied voice saying “Use the Force, Luke” the way Alec Guinness would – except, of course, it’s Liam Neeson getting ignored by a young Skywalker who doesn’t want to hear a “No, Anakin, no!”
He was Sirius Black!