Henk did define the art style and did most of the character design and tilesets for Tiny Thor. He is one of the most popular pixel artists and has contributed with his art to dozens of projects, like Lionheart, Adventures Of Lomax, Contra 4, Shantea 2 and Xeno Crisis.
He is currently working on his own longliving dream project Battle Axe which was successfully funded on Kickstarter. You can also follow him on Twitter.