John Howe is known for his work for the Lord of the Rings.

All images are from http://www.john-howe.com

 You can check out more of John Howe's work on his site.

The Dark Tower

Black Riders

Bilbo's Front Hall

 Horseman in the Night

 Legolas and Gimli at Helm's Deep

The Eye of Sauron

 The Witch King