Rex Barker

 is the Chief Executive Officer of Barker's Baby Foods, one of McMann & Tate's clients. He attends a dinner party at the Stephenses' house with his girlfriend, Babs Livingston. He gets drunk and makes passes at Samantha, so much so that she turns him into a dog in self defense.

Trivia
The name Rex Barker alludes to two characteristics about dogs: Barker refers to the sound a dog makes and Rex (Latin for king) was a popular name for dogs.