Professor Sprout is a minor character in Size Matters. He is a scientist on planet Ryllus who invented the Sprout-O-Matic. Professor Sprout is a short humanoid man with brown-green skin, long and wide ears, glasses, a lab coat, and a plant growing on his head, as well as a short tail with several leaves growing on the end of it.
Professor Sprout met Ratchet and Clank during "Investigate the artifact", as the two ran into him while he was trying to grow a plant with the Sprout-O-Matic. The professor successfully grew a bury blossom that then promptly ate Ratchet, but spat him out before swallowing him. To thank him for helping them with the test, the professor gave Ratchet the Sprout-O-Matic prototype. Just after they left, the plant appeared to turn on the professor.