Gary Oldman's Sassy, Fo Sirius.

Thank you to Melanie who inspired this post, by noting how even though Alan Rickman has tons 'o sass, she has always been partial to Sirius Black, aka Gary Oldman. Well I like Gary too and think he has lots of sass but I've always struggled to identify him in film because he is kind of a chameleon, albeit retaining the sass.
Here he plays Sid Vicious in Sid & Nancy. The look is intense, hard, sexy, and definitely sassy.

Here he is in a more contemporary role as Jim Gordon of Chris Nolan's Batman series, but his look is totally different! Though here he definitely makes sassy professional.

Gary also makes sassy professional in The Contender, thank you Promiti, though here the professionalism is a lot more menacing, and again I can't recognize him!

Bottom line: Gary's got the look. He might not be in the same ranks as Alan Rickman for me, but I got to hand it to him for getting so immersed in every role he does that I can barely distinguish him. Still, thanks to his sassy face, I can sometimes spot him, whether he's a hero or a villain.
Fo Sirius.