What's the theme, including individual rationales?
These are all
Tom and Jerry (Tom Brady and Jerry Rice)
Yosemite Sam (Yosemite National Park + Sam Elliott)
Spongebob Squarepants (@Pugmonkey) (not sure about this; they don't really look like sponges, and Billy Bob Thornton is a weird choice for "Bob".
Charlie Brown (Charlie Sheen)
Homer Simpson (Jessica Simpson hitting a "homer")
SpongeBob Square Pants
Billy Bob Thornton with rectangular (close enough to square) pants that seem to be made out of sponge