Ian is the heavyweight boxing champ.
During the Maximum Tournament, he knocks out Li Mouko in the first round and fights Shiba Chiharu in the second round. The spirit of Ian's stepfather's father (Ian's stepfather is also his boxing trainer) appears to him in order to give him inspiration to continue fighting against the very tough Shiba Chiharu. In the fight against Shiba one of Ian's hands are broken and his trainer throws in the towel in order to protect his boxing career. Despite this, Ian chooses to keep fighting, but he eventually breaks both hands, causing his trainer to run into the arena and restrain him. As a result, his decision is overruled and he loses. He is later knocked out by Yujiro with an uppercut. Baki encounters Ian inside the Arizona Prison. Ian have been trying to become the strongest convict - a dream he gives up on. Before he is released he's beaten by Mouth, only to be rescued by Guevara.
He is clearly based on John Lawrence Sullivan because he describes himself as a bare-knuckle boxing champion with only one loss on his record, and he has a very similar appearance to Sullivan. He may have been based on Mike Tyson. In the English dub, his name is changed to Olam McGregor (perhaps to avoid confusion with the actor Ewan McGregor). During the credits of the second to last episode, he is seen on a flight back home sitting across from Regan