According to IMDB, here are celebrities who share my birthday of April 12.
http://www.imdb.com/OnThisDay?day=12&month=April

Dan Lauria (the dad on “The Wonder Years”)
Ed O’Neill (Al Bundy)
David Letterman (late-night talk show host)
Andy Garcia (the jerk in Ocean’s Eleven )
Scott Turow (writer of law-rific novels)
Tom Clancy (writer of espionage-rific novels)
Beverly Cleary (writer of pre-teen-angst-rific novels)
David Cassidy (Keith Partridge)
Katie Leung (Cho Chang in the upcoming 4th Harry Potter movie)
Claire Danes (Romeo + Juliet, “My So-Called Life”)
Shannen Doherty (“Beverly Hills 90210”)
Vince Gill (country singer)
Herbie Hancock (80s musician)
Alan Ayckbourn (playwright)
Ann Miller (30s & 40s musicals)
Tiny Tim (tulip tiptoer)
Pandora Peaks, Candy Samples, Don Romeo (porn stars)