ALIAS: Black Tom
REAL NAME: Thomas Cassidy
NATIONALITY: Dublin, Ireland
TEAM AFFILIATION: None
AGE: Unknown
POWER: Physical and mental control over plant life, bio-energy blasts
FIRST APPEARANCE: X-Men #99 (in shadow), X-Men #101 (full appearance)

Thomas Samuel Eamon Cassidy, better known as Black Tom Cassidy, has been a steady threat to Generation X. This professional mutant criminal from Dublin, Ireland has a hatred specifically for Generation X's Banshee. To him however, he'd battle his way through anything to make sure his cousin Sean pay for wrongs done to him.

Black Tom Cassidy, who's first appearance was in X-Men #101 (he was seen in shadow in X-Men #99 however), was the heir to his family fortune and the estate of Cassidy Keep in Ireland. He had however managed to wager his fortune and estate and lost to his younger cousin, Sean Cassidy. If that were not enough to hate his cousin, his hatred grew when he lost his love, Maeve Rourke, to Sean. The two married, enraging Tom. Tom turned to a life of crime and made it his profession. He offered his expertise as a gun for hire and while acting as a mercenary, he was imprisoned along with Cain Marko, another mercenary (at the time). They struck up a friendship and Black Tom used his powers to enable them both to escape.

Later on in life, Sean Cassidy was assigned a top-secret mission by Interpol which required that he stay out of touch with his family for a length of time. His wife Maeve was a month pregnant at the time and neither knew of it. During Sean's absence, Theresa (Siryn of X-Force) was born. While taking her to a visit to her relatives in Armagh in Northern Ireland, an explosion by terrorists killed Maeve who had been an innocent bystander. No trace of Theresa was found. In reality, Black Tom Cassidy had been nearby and carried Theresa off with him since he had known of his cousin's sonic powers. He had hoped that his daughter would be a mutant as well and he could help her develop her mutant powers to help him carry out his schemes. Moreover, he saw Theresa as the daughter that he and Maeve should have had, so he took it upon himself to raise her.

At a later time, Black Tom Cassidy once again came in contact with his friend Cain Marko, now called the Juggernaut. They teamed together and began their crime sprees. Cain's hatred for the X-Men, the team that Sean had belonged to before Generation X, helped fuel his hatred for Banshee even more. With this, he forced Theresa, AKA Siryn, into fighting with him against the X-Men. Theresa couldn't accept the life of crime that her "father" had shown her. While in a custody of legal authorities, Black Tom exonerated Theresa of responsibility of her crimes and wrote a letter to Seam explaining who Theresa was. Sean and Theresa were reunited as Tom made his escape.

Later, Black Tom Cassidy and the Juggernaut took the multimillionaire mutants Gideon and Roberto DaCosta, alias Sunspot, prisoners and held them for ransom. X-Force and Cable headed out to rescue them and in the battle, Cable shot Cassidy, inflicting what should have been lethal injuries. Cassidy was taken to a genetic engineering research facility outside of Angouleme France by "Mr. Tolliver" (Cable's son, Tyler Nathan'son) and the injured portions of his body were replaced with a wood-like substance. Black Tom was now able to use these wood parts to focus and channel his bio-energy blasts (originally force or heat blasts). These blasts are strong enough to melt metal. Previously he had to use a wooden shillelagh (like an Irish cane) to project these blasts as wood acts as the focus of his powers. By extending his new roots throughout a wide area he can mentally control all plant life within that area and cause it to grow with immense speed and move as he wishes. He can create a form of human beings from plant matter and mentally control their actions, these form was used in Generation X #25 to assume the form of the GenX kids. Unfortunately the experiment infected him with a genetic virus that continued to increase the wood-like substance in his body, threatening to kill him. Using cell samples from Deadpool, a physician named Dr. Killbrew halted the virus, but not for long. The virus began to spread again, and it was unstoppable. It succeded in spreading throughout his body, transforming him into a sentient plant-like being with superhuman powers. He can sprout branches, roots and plant-like forms from his body. Throughout this experience as his body was mutating, his mind was straining, he slowly went insane.

Now more unstable than ever, Black Tom sought out to kill his longtime rival, Sean. In GenX #25 we see Black Tom had captured most of Generation X. Declaring that he was now the new headmaster of the Acadamy and gardian of the kids, he captured Emma and turned her mind against Sean. In the end, Emma had to use her mind control to make Sean use his sonic power against her, hurting her badly, in order to end Black Tom's threats. Once freed, Sean found out that the kids were taken away, far away from the Acadamy. As Black Tom gloated to Sean on how he placed "his version of Mondo" in amongst the kids, Penace leapt from the shadows and gutted Black Tom down the middle to which his organic body melted into the ground and disappeared. In the pages of GenX, it was assumed that Black Tom was killed, but it wasn't so. He is still making appearances in other comics and still poses quite a threat to Generation X.