Have you seen Bernie?
I wasn’t even planning on saying who I thought was bad in their role, but then you went and reminded me of that absolute travesty of a casting selection. Kevin Costner playing Robin Hood was a complete and utter abomination.
Focusing on the good side:
Edward James Olmos as Commander Adama in Battlestar Galactica
Alan Rickman as Severus Snape.
Ioan Gruffudd as Horatio Hornblower. He was far too good-looking for the role as it was portrayed in the books, but damned if he didn’t nail the the character anyway. I also saw him in a series called “Warriors” about the ethnic cleansing in Bosnia in the 90s and he’s absolutely one of the best actors I’ve ever seen. It’s really unfortunate that he didn’t go on to greater things. I don’t know if he turned his mind to other things, but in a just world that guy should have had a couple of Oscars by now.
nm
Good: Sigourney Weaver as Ripley in “Alien.” Nailed it. Became the model for the tough female heroine.
Bad: The earlier complaint about Rosie O’Donnell as Betty Rubble reminded me of how miscast O’Donnell was as the female cop in “Exit to Eden.” Granted, “Exit to Eden” was badly conceived on every level, and poorly executed on every level, but O’Donnell just plain sucked the sexy right out of the movie every time she was in it. She even made the scene of wrestling half-naked with Imam not sexy! How do you even DO that?
Gene Wilder as Willie Wonka was absolutely wonderful. Johnny Depp as Willie Wonka as positively dreadful.
Could anyone be more Chandler than Matthew Perry?
And Allan Arbus as Sidney Freeman on MAS*H was perfection.
We saw what you did there. 
I think more accurately that would be, “Could anyone be more Chandler than Matthew Perry?” 
Ah, so more properly, I’d say “How you doin?” 
:o I thought he was really cute in it. “ARE YOU EMBARRASSED??” in the video store? Just the perfect goofy foil that made Kate happier than the slick handsome guy she thought she wanted.
Good: Nigel Hawthorne as Sir Humphrey Appleby in Yes Minister/Yes Prime Minister
Very, very bad: Henry Goodman as Sir Humphrey Appleby in the 2013 version of Yes Prime Minister
Just as there is no authentic Batman who doesn’t dance the Batusi, there is no authentic Joker who’s not wearing a Cesar Romero mustache under his whiteface.
What?
Just seconding what gigi said - Black really worked for me, as a contrast to Rufus Sewell’s slimey guy and just his general … American-ness, I guess you could say.
Speaking of Sewell - at first, I didn’t quite buy him as the bad guy in Knight’s Tale because he was so perfect as the romantic lead in Dangerous Beauty. But it turned out to be very good casting indeed, I hated him by the end of it.
Yes. Do you like him? To me, he is remarkably unfunny, and I don’t believe in him at all as the grand master schemer. A reviewer at the IMDB was spot on - “Gone is the restrained diffidence, it is replaced with theatrical ‘mugging’. Sir Humphrey’s new incarnation has 100 times the facial expressions of the original, yet conveys 100th of the gravitas.”
You miss my meaning. A more verbose version of my post would have been something like:
What? They’ve remade Yes, Prime Minister? How dare they sully the memory of the brilliant, perfect original. Someone must die!
Some of them, like Snoop, were actual thugs.
Good casting:
Everyone in the first 2 Godfather movies (it fell apart in the 3rd one)
Joe Pesci and Marissa Tomei in My Cousin Vinny
Jason Alexander as George Costanza
Basil Rathbone was THE Sherlock Holmes. And after paging through two pages (out of 5 so far), I can’t believe anyone hasn’t said R. Lee Ermey for Gunnery Sargent Hartman
Ahh, I see. Watching this remake has actually made me dumber, it seems 
I love him as Horatio. I wish there were more episodes.
He was in Amazing Grace awhile ago and just appeared on an episode of Castle. But I don’t know why he’s not everywhere either.