Squeak is one of mice that apparently live within the Adventure Bay museum.
In "Pups Save Midnight at the Museum", during the Mini-Patrol's sleepover at the museum with Mayor Goodway, Julia and Julius, he accidentally becomes trapped under an antique bowl and is mistaken for Star by Alex Porter. Alex, Little Hootie, Cali and Bunny go searching outside for turtle, only to discover Squeak under the bowl, getting themselves lost in the process, while Mayor Goodway, Chickaletta, Star, Julia and Julius become trapped in the museum by a heavy urn that had fallen blocking their way out. Alex names him "Squeak" due to the mouse habit of squeaking. After being rescued by the PAW Patrol, Alex realizes the helmet and gauntlet that the others thought were being moved by ghosts were actually being moved by Squeck's fellow mice who had become trapped in the armor pieces. Afterwards the PAW Patrol joins the sleepover and Squeak tries to take the plate carrying the snack that Mayor Goodway had handed to Ryder, though Alex stops him and convinces Mayor Goodway to let him stay as Alex has decided to make Squeak a member of the Mini-Patrol, giving him his own Mini-Patrol hat.
In "Pups Save the Cupcakes", Squeak and the Mini-Patrol help Alex locate his missing box of blueberry cupcakes he planned to take to school which Cap'n Turbot had mistaken for the box containing Wally and Walinda's fish treats. After getting stuck in the Flounder's cargo hold, Squeak helps Alex find the box within the Flounder's cargo hold when he moves around inside it which startles a sleeping Cali, alerting Alex to the box's location after Alex who had momentarily forgotten about finding them became distracted by the prospect of a high seas adventure. However the box, Squeak, Bunny, and Captain Turbot are later accidentally knocked into the water after a sleepy Hootie ends up perching on the ship's controls due to tiredness. Fortunately, Captain Turbot manages to hold onto the box Squeak and Bunny were sitting on top of, long enough for Skye, Zuma, and Ryder to arrive and save them, with Zuma using his buoy to catch the box after the Captain's arms got tired, allowing the PAW Patrol to focus on rescuing the Flounder, Alex, Hootie, and Chickaletta.
Despite Squeak being a mouse, he is shown to get along with cats like Cali as he shows no fear while around her (though she has shown no signs of trying to prey upon him herself).
Squeak has grey fur with white markings. He wears a blue hat with a cartoon mouse on it.