A male specimen who struggles to stick with one girl, He insists on giving himself options and is generally regarded to have a good physique. However many girls see through the "Niven cloud" and realise that niven is a total player and really only has one thing truthfully in mind, Sexual intercourse with as many females as possible in the shortest time possible.
person 1: God have you seen that guy?
person 2: yeh he's such a niven
Girl 1: Hell I saw through him ages ago... It doesn't last long