Phineas Nigellus means Black Black

[Catlady (Rita Prince Winston)]

http://www.behindthename.com/ says

NIGEL   m   English
Pronounced: NIE-jel
>From Nigellus, a Latinized form of NEIL. It is sometimes associated 
with Latin niger "black". 

PHINEAS   m   Biblical (Variant), English
Pronounced: FIN-ee-as
Variant of PHINEHAS used in some versions of the Bible. 

Phinehas is Pinhas (Pinchas). I already knew (and Beyond the Name 
agrees) that Pinhas is from the Egyptian name Pa-Nehasi, meaning the 
Nubian (like modern kids are named Scott, Norman, Dane).