Mark Seliger is a favorite of mine. He is a photographer that started photographing musicians for Rolling Stone and now specializes in portrait work.
I follow a lot of Mark's work because even though he has amazing lighting setups he always preaches to not obsess about the lighting. Regardless of a 5 light setup and a huge studio or one light and a small room - you can make an amazing image. The focus when dealing with portraits should be on the moment and the subject. The goal is to bring an emotion out in your image. I try to remember this when photographing my own work.
During the Academy Awards Seliger and his team setup a mini portrait studio and took over Vanity Fair's Instagram. These images were captured during an impromptu photo session at the post Oscar party. This is basically the Hollywood version of a "party" photo booth - sans Groucho glasses and word bubbles.