Guess the name of the fourth actor

A boss was complaining in a staff meeting the other day that he wasn't getting any respect. Later that morning he went to a local sign shop and bought a small sign that read, "I'm the Boss". He then taped it to his office door.
Later that day when he returned from lunch, he found that someone had taped a note to the sign that said. "Your wife called, she wants her sign back!"