Bill Short For?

I have a character who is nicknamed Bill, but William absolutely doesn’t suit him. I know I want it to be a nickname to fit in with his siblings, but I don’t know what else Bill could be short for. Help?

[name_m]Wilbur[/name_m]? [name_m]Wilson[/name_m]? [name_m]Wilfred[/name_m]? [name_m]Wilhelm[/name_m]?

Other than [name_m]Wil[/name_m]- names, maybe [name_m]Abel[/name_m]? [name_u]Or[/name_u] Abilio?