From Sonic Retro
Grounder is a fictional robot in the Sonic the Hedgehog universe, based on the Grounder from the original Sonic 2. He is a loyal, yet dim-witted robot who serves Dr. Robotnik throughout the cartoon Adventures of Sonic the Hedgehog (which is where he is mostly recognised from), along with the chicken-like Scratch. He is a short, green machine with tanklike treads instead of feet. He has a drill for a nose as well as for hands. Grounder specializes mainly in gadgetry; he can turn his drill "hands" into any number of weapons or tools, stores assorted equipment (commonly, a telephone) in his torso, and (according to the episode showing his creation) even has the components of a Swiss Army knife installed in his tongue. Grounder also seems to be the most fragile of Robotnik's robots (himself, Scratch, and Coconuts), getting blown to bits slightly more often than the others.
Despite his best efforts, most of Grounder's attempts to capture Sonic and Tails end in complete failure. His constant failure makes Robotnik shout abuse and threaten him most of the time. Grounder is also easily tricked, as is Scratch; Sonic would often appear in disguise, as anyone from an old lady to a pizza delivery guy. Fooled time and time again by the hedgehog, Scratch and Grounder never really stand a chance, and are mainly used for comic effect.
He is voiced by Gary Chalk.