I don't really have any favorites, actually I agree with everything ForeverFan said. I don't have a favorite, due to the life some of them lead. But here's some:

Actresses
Shirley Temple
Romola Gaira (I like how she acted in Nicholas Nickleby and Amazing Grace)
Georgie Henley
Annnndddd, can't think of anymore..

Actors
Kirk Cameron
Orlando Bloom (In Lord of the Rings only)
Ben Stiller (In Night at the Museum only)
Curious George... Just kidding..

There are some actors who I enjoy watching in any movie, regardless of how good the movie itself is, and here's my list:

Emma Thompson
Shia LaBeouf
Saoirse Ronan
Ewan McGregor
Andy Serkis
Sean Bean
Judi Dench

Andy Serkis is awesome! he is amazing as Gollum in LOTR and also as Capricorn in Inkheart!

Audrey Hepburn-Aside from her acting, I also love her sense of style and,most of all, her compassion for others.

Cate Blanchett- Really is the perfect person to play a queen.

Natalie Portman- I really respect her intelligence.

Kate Winslet-Is always great in her roles

Sean Penn-He really makes you believe that he is a character.

Harrison Ford-Mostly for portraying such iconic characters. It's hard to imagine anyone else as Han Solo or Indiana Jones.
Brad Pitt
Ian McKellan
Alan Rickman

I think nearly all of my favorite actors and actresses are from way back(meaning, I wasn't born when they were filming).
Okay, in no particular order:
Audrey Hepburn--she's amazing. I recently watched Roman Holiday, and she was perfect. It doesn't hurt that My Fair Lady is one of my favorite movies of all time.
Ingrid Bergman--"Here's looking at you, kid." Enough said.
Shirley Temple--she was really cute as a kid, but my favorites are the ones where she's a teenager: Since You Went Away, and The Bachelor and the Bobby Soxer.
Julie Andrews--Sound of Music, Mary Poppins, I grew up watching her on VHS.
Hayley Mills--old Disney movies were a staple during my growing up years and Pollyanna and Parent Trap were favorites.
Katherine Hepburn--she's both funny and dramatic.
Jimmy Stewart--he's just amazing, that's all.
Cary Grant--Arsenic and Old Lace, need I say more?
John Wayne--the classic western good guy.
Colin Firth--he's the Mr. Darcy.

Actresses:
Anna Popplewell and Georgie Henley- they're in Narnia
Bridget Regan- she is amazing in Legend of the Seeker and very beautiful

Actors:
Kirk Cameron- he is awesome in Fireproof and in Left Behind (everyone should watch those movies )
Craig Horner- he is an awesome Seeker and very good looking
Ben Barnes, William Moseley, and Skandar Keynes- they're in Narnia

my favorite actresses:

Georgie Henley
Anna Popplewell
Anita Breim
Abigail Breslin
Annasophia Robb

favorite actors

Josh Hutcherson
Brendan Fraser
Skandar Keynes
William Mosely
Kirk Cameron

I really like those ones too!!! The Narnia ones- Anna is the perfect person for Susan, as she's so experienced and knows Susan like the back of her hand. Will is amazing as Peter- he brings out the character so well. Georgie as Lucy- in the words of Mark Johnson, she would really go into the wardrobe. And Skandar is... well, Skandar. Awesome dude, and he honestly figured out how to portray Ed to the max. Also Abby B. and Annasophia R. in the American Girl movies. I don't know Anita B., Josh H., or Brendan F., but I LOVE Kirk Cameron in Fireproof!!! Awesome movie!

Wow, I don't know if I can really nail down a list of favorites without leaving out 200,000 people, but I'll do my best.

Actors (in no particular order):

Tom Hanks - He's one of the most consistently good actors I know of.
James Stewart - I admit I've only seen him in "It's a Wonderful Life" but it's a brilliant enough performance for him to make my list.
Jamie Bell - Not REAL well known, but he's a fantastic actor.
Adrien Brody
Albert Finney
Johnny Depp - Because he's so versatile and terribly amusing.
Stanley Tucci

Actresses (Again, in no particular order):

Meryl Streep - Because she's a genius
Saoirse Ronan - Just recently became a fan of hers after seeing The Lovely Bones
Kate Winslet - So believable in every role!
Amy Adams

That's about all I can think of now, although I know there are millions more.

I'll always be a,
NL101

I really like those ones too!!! The Narnia ones- Anna is the perfect person for Susan, as she's so experienced and knows Susan like the back of her hand. Will is amazing as Peter- he brings out the character so well. Georgie as Lucy- in the words of Mark Johnson, she would really go into the wardrobe. And Skandar is... well, Skandar. Awesome dude, and he honestly figured out how to portray Ed to the max. Also Abby B. and Annasophia R. in the A

^^ Anita B. is an actress from Iceland who plays Hannah in Joureny to The Center Of The Earth.....
Brendan F. is best known for his role in the "Mummy" films (I have never seen these) and he plays in Journey To the center Of the earth as well!
Josh H. has been in lots of movies.....Bridge to Terabithia being one......and he also is in Journey to the Center Of The Earth! that's him on my avatar!

My favorite actors are:
Dale Dye

My favorite actresses are:
Myrna Loy

SnowAngel

Ah, I somehow forgot Robert De Niro when I was making out my list. While I'm not so much a fan of his recent films, his work in Taxi Driver, Raging Bull, The Deer Hunter, and The Godfather Part 2 are some of the most powerful and poignant acting performances of all time.

Here are some of my least favourits

1. miley cyrus
2. robert patterson

yeah thats about all, their is more but i can't think of them now.

My favorite actresses are: Anna Popplewell, Georgie Henely, and Yvonne Strahovski.

Favorite actors: Will Moseley, Skandar Keynes, Connor Trinneer, Adams Baldwin, Zachary Levi, Michael J. Fox, Avery Brooks, Scott Bakula, and William Shatner.

Actors:
Johnny Depp- One cool pirate
Kirk Cameron- He is a great actor and seems to be a real good guy. We need more good guys in movies.
Skandar Keynes- He is a real good Edmund without a doubt.
Actress:
Kirk Cameron's sister: I forget her name, but she is good too.
Carrie Fisher- I love her as Leia!
The girl that plays Elizabeth on Pirates of the Carribean: Forget her name too, but she seems real charming.

welll...
Viggo Mortensen for obviously being amazing as Aragorn
Colin Morgan for his adorable big ears in Merlin- my favorite show of alllll time! Can't wait for season 3!!
Cate Blanchett for being such a versatile actress I mean who can go from Elven Queen to Queen Elizabeth 1st?