Marshall has spotted white fur covering his body and bright blue eyes. During missions, Marshall typically wears a firefighter helmet and a red vest. He also wears a red pup-pack, which features a water cannon (acting a fire hose). When his spy-medical skills are put of practice, Marshall wears a red cap with a yellow trim (replacing his firefighter helmet), and his pup-pack contains spy-medical supplies such as bandages and a thermometer (in place of the water cannon) This is his EMT uniform.
Marshall is the PAW Patrol's fire rescue dog, and as of season two, its medic. He is prone to clumsily tripping over objects on his way to the team's base. His vehicle is a red firetruck that is able to transform into an ambulance.
- Marshall is revealed to have a large fear of flying in the season one episode "Pups Save a Toof". This trait is retconned in season three, in which he is given flight gear without concern and happily flies in Skye's helicopter.