Black Tom Cassidy

Thomas Samuel Eamon Cassidy is presented in Marvel Comics as an Irish-born mutant whose family history and rivalry with his cousin Sean Cassidy (Banshee) shape his criminal career. He operates as a gang leader and criminal boss, often allied with the Juggernaut, and first appears in Uncanny X-Men #99 (1976). In one storyline he is shot during a battle with Cable and taken to France, where surgeons graft a wood-like substance onto his wounds; that graft begins to spread over his body and ultimately transforms him into a humanoid plant, driving him temporarily insane. In later continuity (the Krakoan Age) Cassidy becomes physiologically connected to the sentient island Krakoa and serves in a security capacity, channeling his powers through Krakoa's facilities and senses.

Early portrayals show Cassidy as a human male who typically carries and fights with a wooden shillelagh, which he uses as a focus for his powers. After being surgically treated with a wood-like graft the material spreads over him and he is described as becoming a humanoid plant — his body covered by woodlike substance and capable of producing vines and plantlike tendrils. In Krakoan-era stories he is depicted as integrated with Krakoa's living terrain; sources describe his physiology as plantlike and connected to the island's flora and topography, though specific visual details beyond 'humanoid plant' and use of vines/tendrils are not provided in the cited material.

Originally Cassidy could project concussive blasts of force and heat through a wooden medium and commonly channeled these through his shillelagh. His powers interact with his cousin Banshee's so that their powers 'cancel each other out on contact.' After the French graft incident he gained the ability to infect foliage and trees, incorporate them into his being, generate plantlike clones of himself and others (including recreating their powers in those clones), control others by latching vines into nervous systems, and siphon life energy via specialized tendrils. Following later continuity events, during the Krakoan Age Cassidy becomes connected to the sentient island Krakoa, which broadens his senses beyond normal reach and allows him to channel powers through Krakoa's facilities and to alter topography and flora (examples given include causing earthquakes and altering plants and foliage). The sources note that after M-Day he lost the ability to transform into a plant while retaining plant-manipulation capabilities in some narratives.