Wolf Ademeit is an absolutely fantastic photographer who focuses on the beauty of animals in zoos rather than capturing portraits of animals in their very own habitats: nature.
He takes the photographs of animals in their artificial surrounding and darkens out the parts that draw attention away from the animals. He then proceeds to post-process the image itself (with the animal in focus). If you love these images, check his gallery out:

Beauty of the Beast
Elephant Games
Fightclub
Giraffes
Kamtschatka bear
Mandrill
Massa
Nandu
Resource
Smile
Speed
The Four
Walk of the Beast