"That was for Halo 2; we were never going to recast them in the first one, because Halo had no cachet, really, until three years later, after it became a million-seller, and then a 2 million-seller," O'Donnell says. "Microsoft had sort of shipped me out to Hollywood shindigs and parties, and they saw that there was a lot of anticipation for Halo 2. I'd be in Hollywood, and I had already been interested in, like, 'Well, maybe I can start casting some actors who are...' I wanted actors who liked games and were already fans of this new game called Halo. I didn't want to get actors who were just looking for a big payday, because there was no big payday."
In the midst of these Hollywood-centric events, O'Donnell was approached by someone from one of the biggest talent agencies, Creative Artists Agency. "One of the guys came up to me at one of these parties and puts his arm around me," O'Donnell recalls. "'Marty, you know, it's time! This is a big deal. You're in the big times now. You've gotta step everything up. We represent Julia Roberts and Tom Cruise.' Now, Tom Cruise was already a Bungie fan, believe it or not; he had played Myth, so this wasn't the first time we'd heard about Tom Cruise. It was this guy basically saying, 'We should make this deal to get Tom Cruise to be Master Chief, and Julia Roberts to be Cortana in Halo 2.'"
According to O'Donnell's recounting of the story, he was less than impressed. "I was like, 'Wow that's really cool! Yeah, thanks a lot,' and I was just like, 'What a slimeball,'" he recalls. "I'm just like, 'Okay, I've got to be really careful in Hollywood, take advantage of who I can, get the people I think are cool,' but I knew that would have ruined everything. The fans would never had accepted – because I know game fans are not necessarily blown away by big stars, they're blown away by solid gameplay and emotionally compelling stories, and they were blown away by what we had done. But they wanted us to stay true to that relationship between us and the fans, and if we just threw Tom Cruise and Julia Roberts, who I would have had a blast working with them – if I could have done that to begin with, maybe that could have been cool – but there was no way that I could replace Jen Taylor and Steve Downes, because the fans already had a relationship with those voices, because they were Master Chief and Cortana. I just could not think of replacing that, so that was never really in the cards to be considered, but I like to dangle it over Jen and Steve every so often, like, 'You know, I could have gotten Julia Roberts and Tom Cruise,' [laughs] It's just a fun story. It never went any further than that one conversation."
Even though the conversation about Tom Cruise and Julia Roberts ended there, it is fun to imagine a world where those celebrities voiced those characters. However, it certainly would not be the same, and likely would have alienated large portions of the fan base. Additionally, they would have almost certainly abandoned those roles by now, as gaming's tumultuous history with one-off celebrity voice actors has shown. Meanwhile, in this timeline, Downes and Taylor still provide the voices for Master Chief and Cortana to this day, even returning to the booth to re-record their lines for Halo: Campaign Evolved, which gave them a chance to deliver their now-iconic performances with more perspective on the characters and franchise as a whole.