Derek

Derek is the English short form of Diederik, which is the Low Franconian form of Theodoric, an old Germanic name that means “people-ruler”.

Curtis

As a given name, Curtis is English given name. As a family name, it’s Anglo-Norman.

Patrick

Patrick is the English form of Pádraig from Celtic, derived from Patricius (Latin). (Also Wikipedia says it’s German, but gave no explanation?)