Peter Potamus (voiced by Daws Butler impersonating Joe E. Brown) is a purple potamus exploring the world in his time-traveling hot air balloon with his sidekick, So-So. When faced with a certain situation, Peter uses his Hippo Hurricane Holler technique to blow away his opponents. In Harvey Birdman, he is a lazy hippo who only hangs around the office to eat, make out with chicks, and ask if anyone's ever got that thing he sent them.
I'll be real for a second; I only like his Harvey Birdman take on Peter. No offense to Daws, Joe and William of Hanna Barbera, but Peter's original performance is just by the numbers "cartoony comedy animal".
With that said, Daws Butler does his best, and I have to commend him for bringing energy and personality to Peter. He gives him kind of a dopey voice that's kinda fun to listen to.
Greg Burson (the main man who's taken over for so many other of Daws' roles) plays Potamus in Yo Yogi. His take is a bit higher and you can tell some of his Yogi slips in, but he's mostly gotten Daws' take down pat.
Jeff Bergman plays him in a World Premiere Toons short, he's alright. I can't say too much of him.
Joe Alaskey dons the yellow safari hat in a brief cameo in one of the earlier Harvey Birdman episodes. He sounds rather low-key, and while it's a nice change of pace, it doesn't leave too much of an impact.
Chris Edgerly is where the character really shines for me. He's a hilarious lazy oaf who hogs every scene he's in, and really makes the character his own. My vote's for Chrissy.