Mad Dok Grotsnik is, like most other Ork Painboyz, completely insane and obsessed with "serjery". He has experimented on himself so much that he has become even more resilient (and demented) than most other Orks. His implanted bionik weapons make him a fearsome killing machine in close-combat. He is more than willing to experiment on any hapless Ork who ends up on his operating table.
Grotsnik is best known as the Dok who performed surgery on Ghazghkull Mag Uruk Thraka when the future Warboss received a bolter round to the head, replacing a large chunk of his skull with adamantium, which led to Ghazghkull's communion with Gork and Mork and his subsequent dominance. Despite the general unpopularity of Grotsnik's wanton surgery, no Ork would dare to harm him while he is under Ghazghkull's personal protection.