Randy Hanrahan was once a promising football player for the Dallas Cowboys, but suffered severe injuries to both his knees during a pre-season game ending his career permanently. Following this, he gained employment through the Penguin, in the Iceberg Lounge as a bouncer, where he enjoyed being able to inflict violence and get paid for it. Eventually Penguin gives him a promotion of sorts, giving him the title of reposessor of defaulted loans, which he enjoyed for years. He eventually leaves, making himself an assassin for hire, during which he traveled until eventually coming to Bludhaven where he came into the employ of Bludhaven crime lord, Blockbuster. He attempted several times to claim his employers open contract several times on the vigilante Nightwing, who has made Bludhaven his new home but failed.

Following this, Blockbuster attempted to finish Nightwing by partnering Stallion with other assassins in his employ, frequently putting him with Brutale and Lady Vic. However despite the numbers they were still unable to complete the contract, forcing Blockbuster to bring in a new assassin Shrike into finish the job, following him easily defeating the three assassins.

Stallion is eventually killed, when he is in the city in a bodyguard capacity when the Society drops Chemo on Bludhaven.