Have there been any actors who have voiced a character in animation and then gone on to do play them in a live action production?
Three that spring to mind are Evan Richards, Christopher Kennedy, and Rick Overton. In the second season of the Bill and Ted's Excellent Adventures
animated series, they took over the roles of Bill, Ted, and Rufus (replacing the original film's stars who had voiced those roles in the cartoon's first season), and then went on to play those same characters in the brief live-action Bill and Ted
TV series. I've always wondered how that came about. It's kind of mindboggling -- two sets of actors have played those three characters, and each set has played them in both live action and animation. That's gotta be unique.
Another recent example is Daran Norris, who plays Timmy Turner's father in The Fairly Oddparents
and has reprised the role in the two live-action TV movies thereof.