The ultimate betrayal! Check out the biggest celebrity cheating bombshells through the years -- including scandals involving Kristen Stewart, Tiger Woods, Katharine McPhee and Ashton Kutcher.
Woody Allen and Mia Farrow
A scandal that once rocked Hollywood. Legendary director Woody Allen shocked everyone when it was revealed in 1992 that he was romantically involved with Soon-Yi Previn -- his stepdaughter, and the adopted daughter of his longtime love Mia Farrow. Allen never officially adopted Previn, and the two eventually married in 1997. The couple have two children together.