At least, according to www.broadwayunderstudies.com
The list includes Hunter Bell (HOW THE GRINCH STOLE CHRISTMAS), Jeff Daniels (GEMINI), James Gandolfini (A STREETCAR NAMED DESIRE), Hope Davis (TWO SHAKESPEAREAN ACTORS), J. Robert Spencer (SIDE SHOW), Brian D'Arcy James (CAROUSEL), Alice Ripley (THE WHO'S TOMMY), Stockard Channing (TWO GENTLEMEN OF VERONA), Sutton Foster (LES MISERABLES), Zach Grenier (MASTERGATE), Hallie Foote (A LITTLE FAMILY BUSINESS), Marc Kudisch (JOSEPH...DREAMCOAT), Gregory Jbara (BORN YESTERDAY), Will Swenson (110 IN THE SHADE), Christopher Sieber (INTO THE WOODS), Jennifer Damiano (SPRING AWAKENING) and Karen Olivo (RENT).
Yes. They, like most big theatre actors, were once understudies.
"If this is going to be a Christian nation that doesn't help the poor, either we have to pretend that Jesus was just as selfish as we are, or we've got to acknowledge that He commanded us to love the poor and serve the needy without condition and then admit that we just don't want to do it." -Stephen Colbert