From Denmark or a Dane
Derived from the Old Norse name Danr, it was originally an ethnonym used to describe a person from Denmark. In Germanic and Scandinavian mythology, it is also the name of a dwarf and a stag. It has a long history in literature, appearing in both ancient sagas and modern fantasy epics.
Less common today
Dain isn't in the latest US Top 1000. It last peaked at #1,523 in 1990.
A heroic Dwarf King of Erebor Β· The Hobbit
Olympic gold medalist in beach volleyball
US births per 5-year period, 1990βpresent (SSA data).