FOR
REAL: Derek started out as a form of the Old german name Theodoric, which is derived from elements meaning "power" and "people." Derrick is the English surname form.
diminutives: Dery (rare), Rick
related names: Theodoric
Other recorded spellings: Derick, Dereck, Deric, Derik, Darrick, Derrek, Derrik, Deryk, Derreck, Derric, Darek, Darick