Let's make a top 5 list of our favourite actors or actresses.
Here is mine: (the lower number the better)

1. Will Smith
2. Vin Diesel
3. Adam Sandler
4. Nicolas Cage
5. Jim Carrey

It's not easy… I like a lot of actors… but just to choose a few:

1. Bill Murray
2. David Duchovny
3. Scarlet Johanson

actor
Depp
Carrey
Nicholson
Pitt
Phoenix
Hrusinky
Jackman
Ledger
Niro
Pacino

actress
Blanchett
Portman
WInslet
Witherspoon
Deschanel
Bledel
Kidman
Carter
Foster
Kunis

tom hanks

Sigourney Weaver

Heath Ledger
Tom Hardy
Josef Fassbender
Colin Farrell
Paul Bettany
Richard Armitage
Kate Blanchet
Kate Winslet
Helen Mirren
Carrey Mulligan
Renee Zelweger

Nicholas Cage
Adam Sandler

Jennifer Garner

one of the best is defo Tamer Hassan

Matthew MacFayden. He can be a perfect gentleman (Little Dorrit BBC series) as well as a cute shy fellow (Death at the Funeral).
Toby Stephens
Helen Bonham Carter
Emma Thompson
Rowan Atkinson

My favorite actress is Nana Visitor and actor Alan Rickman

Ondra Vetchý, Jan Kraus and Luis de Finess and also actors playing Sheldon an Rimmer.

You love more the characters (Sheldon, Rimmer) than the actors, don't you?

I do and more importantly, I don't remember the actor's names. :--]

I know it well. An actor/actress becomes my favourite after I see him/her playing some character I like. Since I don't know their real personality at all, it is a natural process I think…

Well, if I like an actor playing a particular character and I want to see whether I like the ACTOR AS SUCH, I usually check out some bonus features on the DVD or watch an interview on David Letterman's show (or Craig Ferguson etc.)…

And then it's easy to say whether it's the actor I like or just the role he/she's in.