|night owl or night hawk|
|informal a person who is or prefers to be up and about late at night|
|night hawk or night hawk|
A person who habitually stays up late and is active at night, as in You can call her after midnight, for she's a night owl. This colloquial term, originally used in the late 1500s for an owl that is active at night, was transferred to nocturnal human beings in the mid-1800s.