I'll take:

1. Adam Baldwin (especially as Jayne)

2. Hugh Jackman (only as Wolverine)

3. Goran Visnjic (anytime, anywhere)

4. Wil Wheaton (not my number one right now, but the longest running member of my list)

5. Eric Szmanda (my favorite CSI)

And just missing the Top 5 list:

6. Mark Ruffalo

7. Jesse L Martin

8. Jeremy Northam

9. Paul Giamatti

10. Jon Stewart

I reserve the right to edit this list, cause it's MY list.