Sometimes an accent is needed to play a character from a different nationality or time period.
Though some Hollywood stars smoothly transform, others have struggled to give convincing performances. From Leonardo DiCaprio in "Blood Diamond" to Angelina Jolie in "Alexander," some actors have gone painfully wrong. Even classic films like "Mary Poppins" aren't immune to the dialect failure -- Dick Van Dyke's weak cockney accent made viewers want to stick their heads in a chimney.
What other actors have been deemed accent destroyers? Take a look through the slideshow below for 10 of the worst movie accents.