Maxwell Tennyson (Ben 10 UAF)

Grandpa Max is a retired member of the Plumbers, an intergalactic police force charged with regulating alien contact and keeping the peace. His two grandchildren, Ben and Gwen, help Max Tennyson investigate mysterious alien occurrences, but gone missing two years ago while battling the Highbreed. To have any chance of finding their grandfather, Ben and Gwen decided to unravel the case he was working on and succeeded.

Ben 10 Ultimate Alien Force
He is one of the main heroes.