Big Sir is a DC Comics character. He first appeared in The Flash #338.
Born Dufus P. Ratchet, he has a malformed brain gland that caused him to grow to incredible proportions but left him mentally retarded. He was later abducted from his mental hospital home by a group of supervillains who equipped him with an high-tech suit of armor created by the Monitor. This suit was heavily armored, could fly, and included a powerful energy mace. However it also telepathically made him susceptible to suggestion. Big Sir has been used as a henchman or minion by all manner of supervillians throughout his career. He later joined the Suicide Squad in return for a pardon, where he was killed in action.