Where does “Finn” come from?

Finn (Danish) comes from Old Norse Finnr, from Proto-Germanic Finnaz.

Ancestry of “Finn”, step by step

Step	Language	Word	Meaning
1	Old Norse	Finnr	a Sami; Sami, Finns; a {{m\|en\|Finn}}, a...
2	Proto-Germanic	Finnaz	—