Ratso

Ratso is one of the major characters from The Brave Little Toaster Goes to Mars and The Brave Little Toaster to the Rescue. He is voiced by Andy Milder.

The Brave Little Toaster Goes to Mars
Here, he is shown to be very kind and helpful to Toaster and the other appliances. He stays behind and stands watch while Toaster and his friends go on a mission to rescue Robbie, who is referred to as the "Little Master" by the appliances.

The Brave Little Toaster to the Rescue
Here, he is first shown to be always grumpy and angry, as if mad about being kept as a pet. He's rude to pretty much everyone, but he eventually does come through in the end for Toaster and his friends, while also putting himself at great risk.

Trivia

 * Ratso bears some resemblance to The Rat from Lady and the Tramp, but unlike Ratso, he's an antagonist.