Sullivan was Jenner's minion and the anti-villain in The Secret of NIMH, though he doesn't like the latter's idea of killing Nicodemus. He eventually was on Justin's side. He was voiced by Aldo Ray.
Role In The Film
Sullivan is first seen in the Rose Bush among the Council of Rats. It is here he voices his little concern about moving the Brisby home; stating: "We've got problems of our own, let the lower creatures fend for themselves.".