Richard Henry Mardukas

Richard Mardukas is an overly protective aide of Tessa's who insists on guarding her with his life. He holds the rank of Commander and is in charge of Mithril's TDD-1 when the Captain, Testarossa, is not on board; appropriate, given that Mardukas' position is that of Executive Officer. Mardukas is often seen wearing a hat bearing the name of the HMS Turbulent (S87), a real British submarine.

(Source: Wikipedia)