Off my head it is Stripes. His chuga-luga scene comes to mind when the band of misfits perform their cadence on graduation day from boot camp. But, that is a scene. The movie that comes to mind for a character is Caddyshack.
Wow! I could not remember all the movies I had seen him in so I peeked at Wikipedia. He did 60 since 1976. He has four on the back burners today for 2016. Reading them over one of the first he did really is a memorable film Meatballs - 1979. That movie left me with an impression he was an actor with a heart, even though I knew it was a character.