This guy and Peter Griffin 
Jan Smither and Marcia Strassman (Mrs. Kotter). Out of character they don’t look that much alike but they both played mousy brunettes with glasses in different 70s sitcoms, so I tended to mix them up…
Comic and 70s era Hollywood Squares regular Marty Allen
http://www.martyallen.net/KK_KM5.JPG
and those little troll dolls
http://learning.cc.hccs.edu/Members/cschweitzer/images/troll.jpg
Christian Bale
http://upload.moldova.org/movie/actors/c/christian_bale/thumbnails/tn2_christian_bale_2.jpg
James Brolin
Wow I can’t believe no one mentioned Aaron Eckhart and Viggo Mortensen
Russell Crowe and 50s rocker Eddie Cochran.
Rapper/Actor Will Smith
http://www.aolcdn.com/ch_kids/will-smith-400a314.jpg
and
Webcomic Gene Catlow
http://www.voyd.com/ia/dolinsky_files/image024.gif
English actress Samantha Morton (Control, The Libertine, Minority Report, Sweet and Lowdown) and English actress Emily Watson (Breaking the Waves, Red Dragon, Gosford Park, The Proposition).
USA hockey greatMike Modano and Napoleon Dynamite himself,Jon Heder.
Traditional Irish folk singer Tommy Makem
http://dynimg.rte.ie/0000f9ea10dr.jpg
and Dr. Zaius from Planet of the Apes
Uncanny!
The young **David Hemmings ** (circa Blow-Up, before he blew up in middle age) looked like a cross between **Oskar Werner ** (Fahrenheit 451) and Richard Burton.
Andy Roddick and Sean William Scott (Stifler).
Jennifer Morrison (House) and Ginnifer Goodwin (Big Love).
How about Red Hot Chili Peppers drummer Chad Smith and actor Will Farrell? Link
This site has more examples of celebrities separated at birth.
Psst, wanna hear something funny? Chad’s middle name is Gaylord 
Anthony Zerbe and Tyne Daly.
UK actresses Samantha Janus and Sarah Alexander (in the middle)
