Groote

 was a scientist who worked on the Schrödinger Institute.

Groote worked with Tasdevin, who was ostensibly working on a perpetual-motion machine. She was horrified when she learned he was attempting to stabilise space-time to give himself immortality.

Tasdevin's experiment caused a temporal echo in which the Doctor and Guinevere Winchester were caught. Before the Doctor ended the cycle, he and Guin witnessed an echo of Groote follow Tasdevin into the lab in a vain attempt to argue him out of continuing his experiment. (PROSE: Revenants)