I'm a big fan of Andy Gotts. 

He is a great celebrity portrait photographer, of course, but he seems to have a special talent to bring out something special out of his subjects, might it be their silly side or deep emotions. Even though his subject are mostly (very) famous actors. His work is very refreshing in the world of tiresome beauty of perfection. 

I was curious how he does it so I did some digging. In one interview Andy tells us just to 'chat to them!', find out what they are about, what makes them tick and laugh. Then just keep chatting and shooting... Some spontaneous priceless moments might just happen. Here, among other stories, Andy describes such a moment when he got the famous shot of Robert the Niro (highlighted in red):

"At the very end of the shoot I asked Bob how he feels about people doing  impersonations of him, especially his famous quote from Taxi Driver. He  asked if I had seen Al Pacino doing an impression of him, to which I  said no. All of a sudden, he squinted his eye and with an  ever-exaggerated downturned mouth, he started bellowing: 'Are you  looking at me?' Through my tears of laughter I took only a couple of  shots." Source: BBC In Pictures

This very contact sheet of Robert De Niro can be examined and admired at The Unseen Collection at The Showroom Presents in London until the end of July. The exhibition also features Penelope Cruz, Kate Winslet, Robert De Niro, Harrison Ford, Benedict Cumberbatch, Julia Roberts and other great stars.

Each contact sheet shows a series of photographs taken in one sitting, all untouched (Andy Gotts is one of the few photographers who famously refuses to retouch and photoshop his portraits). The frames that have been shown before are highlighted. 

Priceless.