Mr. Porter is Alex's grandfather, but it is unknown which parent's father he is. He stops Alex from doing dangerous things like running on ice, running out onto the street, or breaking a bone. According to Alex in "Pups Pit Crew", Mr. Porter always fixes things with a lot of duct tape.
Mr. Porter is the kind of the uncle or grandpa one would desire. He's nice, loving, wise, and caring towards others, especially Alex. He passes down ideas for Alex, but it usually doesn't turn out right for him. He is level-headed and does his best to keep Alex out of trouble. Alex's well-meaning efforts to help (as well as his impulsivity) can negatively influence him, but he still loves him all the same.
Like Marshall, he can be clumsy. He frequently trips over things such as food left on the ground, and will often fall down when he's carrying food intended to be served to someone. He's somewhat prone to bad luck, such as getting his butt stuck in a stump and getting sprayed by a skunk in "Pups Save a Surprise".
Mr. Porter has pale skin and dark brown eyes. He has no hair, but he does have a set of eyebrows, a mustache, and a "soul patch". He wears a light blue shirt and a green apron. He is as tall as other adults like Mayor Goodway.
Here is a gallery of Mr. Porter's attires: