Isn't "nil" a slang way of saying "nothing."
Just because I like a challenge, names from which Nil could be derived:
Niall ("nile")
Nils ("neelz")
CorneliusNicholasNigelNevilleLionelNathanielDaniel /
Danilo
By the way, I met a woman once whose nn was Nilly / Nillie. it was short for
Nilofer (sp?), a Persian girl's name.