Worst Performances: Xanadu (1980), Two of a Kind (1983)

As a singer, Olivia Newton-John held it down for over a decade, winning four Grammys, dropping 10 Billboard-topping singles, and releasing that timeless classic of sexual innuendo "Let's Get Physical." With those musical statistics under her garter belt, the perky blonde should've been content with dominating one entertainment industry, but, alas, she got greedy and has since given acting several tries.

The results, while never dull (Xanadu, for instance, is enjoyably disastrous), and mostly of the musical variety, drill home the fact that she's at her best when belting out spirited vocals. In other words, singing more than actually acting.