Nail is a fighter and the personal bodyguard of Guru; the Namek elder. He is very strong and not including Piccolo he is the strongest Namekian on planet Namek.
Although defeated by Frieza he still managed to survive long enough to fuse with Piccolo. The permanent fusion with Piccolo caused Nail to lose his own body and drastically increased Piccolo's power level.
In the English dub version of the Dragon Ball Z anime series Nail was originally voiced by Michael Dobson when the Ocean Group worked with Saban and Funimation.
When Funimation dubbed the series Nail was voiced by Sean Schemmel for all future episodes and also for the uncut DVD episodes.