Which Pixar film introduced the character Mater?

Cars introduced the character Mater.

Mater is a rusty tow truck from Radiator Springs who becomes Lightning McQueen’s closest friend. He first meets Lightning after the race car is ordered to repair the town’s damaged road. Mater’s openhearted personality, unusual stories, and loyalty help McQueen move beyond his early arrogance.

The character is voiced by Larry the Cable Guy, whose comic delivery became one of Mater’s defining features. Mater’s design is based on an old tow truck, and his name is a playful shortening of “tomater,” reflecting the Southern-inspired speech and humor associated with the character. His friendship with McQueen is central to the first film’s emotional transformation.

Mater returns in Cars 2, where he becomes unexpectedly important to the spy plot, and in Cars 3. The character was not introduced in a Toy Story film, although both franchises are Pixar productions. Cars premiered in 2006, making it the film that established Mater and the wider Radiator Springs cast.