One of the skills many actors develop is the ability to impersonate popular personalities (proving the old adage that imitation is the most sincere form of flattery). Whether mimicking famous celebrities or cartoon characters, a talent for voices demonstrates the added value of an actor's sharp ear combined with an uncanny ability to improvise on a moment's notice.
The late Robin Williams was a master of vocal shapeshifting, capable of popping in and out of various personas with split-second timing. Others have performed such tricks with equally remarkable skill. Consider the eerie talents of Kevin Spacey and Seth MacFarlane.