A persistent rumor that Tom Cruise was nearly cast as Master Chief and Julia Roberts as Cortana for Halo 2 has been debunked by the game's former voice director and composer, Marty O'Donnell. O'Donnell explained that while there was a brief conversation about the possibility, it never progressed beyond a casual discussion at a Hollywood party.
The story gained traction after Halo's Master Chief voice actor, Steve Downes, mentioned on his YouTube channel that Tom Cruise had been discussed as a potential candidate. This stemmed from Microsoft's desire to elevate Halo 2, especially after the success of the first game. O'Donnell himself was encouraged to attend industry parties in Hollywood as Microsoft sought to capitalize on the sequel's anticipation.
It was at one such event that a casting agent, representing both Cruise and Roberts, approached O'Donnell. The agent suggested a deal to cast Cruise as Master Chief and Roberts as Cortana, noting that Cruise was already a fan of Bungie's earlier game, Myth. O'Donnell recalled the agent's enthusiastic pitch, stating, "We represent Julia Roberts and Tom Cruise."
While O'Donnell acknowledged Cruise's existing connection to Bungie's work, he stated that he never seriously considered the casting. He explained that his immediate internal reaction was, "I knew that would have ruined everything." O'Donnell believed that the success of Halo was tied to the game itself and the relationship players had with the established characters and their voices, rather than the allure of celebrity actors. He felt that replacing the original voice actors, Jen Taylor as Cortana and Steve Downes as Master Chief, would have alienated the fanbase.
O'Donnell shared that he occasionally teases Downes and Taylor with the "what if" scenario of casting Hollywood stars, describing it as a "fun story" that never materialized beyond that single party conversation. The original Master Chief and Cortana voice actors have since repris ed their roles for Halo: Combat Evolved Anniversary.