The Screamin' Banshee is a character in Mater and the Ghostlight.
"The Screamin' Banshee lurks outside Radiator Springs in Ornament Valley. The Banshee waits for anyone who wanders out alone in the darkness of night. He is rarely spotted but is well known through myths and legends. Nothing can make the Banshee show fear. However, he is a bit puzzled by Mater."
He was seen at the end of Mater and the Ghostlight, with Mater in front of him. However, Mater doesn't know that it's the Screamin' Banshee and warns him of him. Then, he says goodnight and drives away.