Where does “elf” come from?

elf (Old English) comes from Proto-Germanic albiz, from Proto-Indo-European albʰós — white.

Ancestry of “elf”, step by step

Step	Language	Word	Meaning
1	Proto-Germanic	albiz	elf, fairy
2	Proto-Indo-European	albʰós	white

elf — Etymology, Origin & Word History | Etymology Explorer