Tim

Tim is a Caster skeleton found in the Underground. He can be recognized by his Wizard Hat. Just like any other caster, he will randomly teleport himself to a visible part of the screen after shooting three projectiles. Tim was added as a rare spawn during the 1.0.3 update. As of the 1.0.4 update, Tim's spawn rate has been reduced.

Drops

 * Wizard Hat: 100% (1:1 chance)

Finding Tim
Tim can be found anywhere in the Underground and Caverns layers. Its spawn rate is very low and completely random, but it seems to increase with Depth.

Trivia

 * His name is a reference to Tim the Enchanter from Monty Python and the Holy Grail, this was confirmed by Blue on the Terraria IRC.