Zachary was the boxer in The Fix who knocked out Terry Foley, leading to House trying to prove that Foley had a medical condition that made him unfit to fight. He was an unseen character.
House and Wilson had bet on the fight with House taking Foley and Wilson taking Zachary. Zachary won in a first round knockout and Wilson gleefully showed up in House's office the next day to collect $50. However, House reneged, saying that it was obvious that Foley had passed out, not been knocked out. However, even Foreman was incredulous that House had bet against Zachary in the fight.