Actors Who Make Me Want to See a Movie When I Find Out They're In It, Even If I Specifically Didn't Want to See It Before and Know It Will Be Stupid:

*in no particular order
**and when I say "favorite," I don't necessarily mean the movie--just the actor's role in that movie

I think Meryl Streep is one of the most elegant people alive. Her voice is beautiful and totally underappreciated in her career; actually, she and Madonna used to be up for a lot of the same roles, including Eva Peron in Evita.
Favorite: Mamma Mia, Julie & Julia, The Hours. Least favorite: Adaptation. Top of the to-see list: Postcards from the Edge, The Iron Lady, Lions for Lambs.

Helena Bonham Carter would be incredibly intimidating to me in real life. She's a brilliant actor, and I love that she can play total lunatic (Bellatrix Lestrange, the Red Queen) as well as absolutely normal (Queen Elizabeth, Mrs. Bucket). She's pretty much the epitome of cool.
Favorite: The King's Speech, Harry Potter, Fight Club. Least: Terminator Salvation. To-see: Les Miserables, Toast, Twelfth Night, Howards End.

Emma Thompson is sort of sneaky in her awesomeness. She never seems to be the point, you know? like even when she's in a leading role, she's just sort of understated. So you have to be paying attention to know how funny she can be, in addition to that understated elegance.
Favorite: Much Ado About Nothing, Love Actually, Stranger than Fiction. To-see: Pirate Radio, An Education, The Remains of the Day, Howards End.

I feel like I want Minnie Driver to be my best friend. She's good in a serious role, too, but mostly I love when she makes me laugh, playing amazing characters like Carlotta in The Phantom of the Opera. I wish she were in more movies.
Favorite: Good Will Hunting, An Ideal Husband. Least: Ella Enchanted. To-see: Princess Mononoke, Take.

I haven't even seen Emily Blunt in that many movies, and some of them--like The Adjustment Bureau--were fun, but not anything special. But I really like her quirky attitude. 
Favorite: Sunshine Cleaning, Wild Target, The Devil Wears Prada. Least: Gnomeo & Juliet. To-see: Charlie Wilson's War, The Young Victoria. 

Well, I do not think this needs to be explained. Tina Fey is one of my heroes, and she is a comic genius. I want her to be in more movies, and I don't even care if they're all silly--a movie can be total crap, but if Tina Fey is in it, it's still worth seeing.
Favorite: Mean Girls, Ponyo, and of course, 30 Rock. Least: The Invention of Lying. To-see: "Elmo and the Bookaneers;" all the episodes of Saturday Night Live that I haven't seen yet.

Alec Baldwin has become one of my favorite actors since I started watching 30 Rock. I love his satirical humor, and I think Jack Donaghy is probably one of the top ten best TV characters ever.  
Favorite: 30 Rock, The Aviator, Madagascar 2. Least: Saturday Night Live: The Best of Alec Baldwin (oh, some of it is so funny, but the gay sex jokes are just too too much for me). To-see: The Good Shepherd, The Royal Tenenbaums, Running with Scissors.
 
I don't really know what it is about Alfred Molina, but I love seeing this guy in movies. He's brilliant as a villain, but somehow I always find myself liking his characters even as I hate them.
Favorite: Chocolat, Maverick. Least: Spiderman 2, Abduction (I say this with the intent to never, ever watch this movie). To-see: Vivaldi, Poe, Frida, Magnolia, Anna Karenina.

Ah, Cillian Murphy. I find this guy incredibly attractive, I'm not gonna lie. Whether he's a villain or not, I am just intrigued by that completely un-macho intellectual persona.
Favorite: Batman Begins, Inception. To-see: Intermission, The Wind that Shakes the Barley, Cold Mountain.

So, Mike always makes fun of me for how much I love Jeff Goldblum. He says "You've barely even seen him in anything!" Which is sort of true, actually, but the things I have seen him in are just awesome.  
Ultimate favorite: the episode of Friends where he plays Leonard Hayes. Also: Independence Day, The Switch. To-see: Morning Glory, Man of the Year, Mini's First Time, the 1980 TV movie of The Legend of Sleepy Hollow in which he plays Ichabod Crane.

Stanley Tucci is actually one of my very favorites, and I wish he were in more movies! I love the characters he plays and I swear he's the kind of guy I just want to be my best friend, or my favorite uncle.
Favorite: Easy A, The Devil Wears Prada, Shall We Dance. Least: The Lovely Bones. I have not seen this, and I will not, because I saw a trailer and have read part of the book and know that he will be too, too good as that awful creepy man and I cannot have that creepiness associated with Stanley Tucci in my head. To-see: The Hunger Games (!), Burlesque.

I just like Michael Caine a lot. I like the fact that he was a hotshot playboy in the 60s, and I like that he plays nothing but crotchety old men now that he's older. (He does crotchety old man really well.)  
Favorite: The Prestige, The Muppet Christmas Carol, Miss Congeniality, The Eagle Has Landed. To-see: Alfie, The Man Who Would Be King, Hannah and Her Sisters.

Paul Giamatti makes me happy. There's something endearing about him, and I always want to like his character no matter what.
Favorite: Cinderella Man, Lady in the Water. Least: Saving Private Ryan. (This is a cop-out because it's not really a Paul Giamatti movie; also, I didn't hate it, but was traumatized by it and never want to watch it again.) To-see: Ironclad, Barney's Version.

I don't think I'd seen Robert Downey Jr. in anything before Iron Man. (Just kidding--one movie.) Most of my thoughts about him are based off of three movies (and only two characters), but he does those characters really well and I think he is fabulous. I am a fan of that dry clever wit. ("You wear a jacket.")
Favorite: Sherlock Holmes, Iron Man. Least: Due Date. To-see: Good Night and Good Luck (have seen this, but before I knew who he was), The Avengers, The Soloist, Chaplin, Sherlock Holmes 2.

Leonardo DiCaprio is a funny one for me--I was in love with him in eighth grade, when Titanic came out, and then when I got older I was embarrassed about it so I specifically didn't like him, but now that he's older he's actually become a really fantastic actor and I know that any movie starring him is going to be interesting and substantive.  
Favorite: Inception, Shutter Island, The Aviator, The Departed. Least: Guess! To-see: J. Edgar, The Great Gatsby, Gangs of New York.

Emma Stone is funny. She's smart. And I loved her enough in Easy A that ever since then, I'm interested in anything that she's in. It is also awesome that she keeps working with others who are on this list.
Favorite: Easy A, Crazy, Stupid, Love. To-see: The Help. (And then only things going forward, because I'm not interested in anything she was in before Easy A.)

I just remembered Maggie Gyllenhaal. She's another one that I would love to know in real life; her characters are always so daring and snarky and laid-back, and she just seems like a lot of fun. Any time I see her name in the cast, I'm more interested than I would have been. (Does anyone know if it's a coincidence that she's in so many movies with Drew Barrymore? I've seen three on IMDb already.)
Favorite: Stranger than Fiction, Mona Lisa Smile, Away We Go. To-see: Paris, Je T'aime, Learning to Fly, Donnie Darko.

Thanks to Lori, I have also remembered Cate Blanchett, who is another new-ish favorite.  Her place on this list dates to when I first saw The Aviator, and she was amazing as Katharine Hepburn (my number one favorite actress of all time, but I only included living actors on this list).
Favorite: Lord of the Rings, The Aviator, Robin Hood, Hanna. Least: Indiana Jones and the Kingdom of the Crystal Skull. To-see: The Talented Mr. Ripley, Elizabeth, The Shipping News, The Curious Case of Benjamin Button (which I've been avoiding because the idea kind of creeped me out, but now I'm interested in watching because I like her).


Honorable mentions (aka I find them really attractive):

In a few days I'll be doing the opposite of this collection: actors who make me NOT want to see a movie, even if I'd wanted to see it before I found out they were in it. Who are your favorites?