Chris O'Donnell has gone from "School Ties" heartthrob to full-grown hottie!

The birthday boy was only 22 when he costarred in the 1992 movie about a prep school student (Brendan Fraser) who keeps his religion a secret -- and today, he turns 43.

Luckily for Chris, he's been pretty successful ever since, with big roles in "Batman & Robin," "Mad Love," "Grey's Anatomy" and "NCIS: Los Angeles."

His costars all fared fairly well for themselves too, winning Oscars, starring in huge blockbusters and a very well-known Broadway musical.

Of course, it hasn't been great for everyone.

Check out the gallery above to see which star is currently serving prison time -- plus, find out what the rest of the cast looks like now.

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