Mud is a one of the prisoners in The Old Camp, where he can be extremly annoying to you from you encounter him til you... get rid of him.
He follows you all the time, and once in a while interrupts your walking by asking your questions or just talk to you. Some of the things you will learn about him, if you let him talk to you, is that he was not liked by his parents, and why he was thrown into The Colony.
Officially Mud only appear in Gothic as an encounter, but with a hack (using a code in MARVIN-mode, he can re-appear as a zombie in Gothic II.
Mud might be one of the most known non-key characters in Gothic - for his reasons...