They look so damn similar, from the style and color of their armor down to their behavioral traits. Seems like Bungie simply saw the success that Doom had over their Marathon series and thought to themselves “you know what our next game needs? A massively overpowered super soldier in green high tech armor who spouts sarcastic one liners in the face of an overwhelming alien invasion” and went to town with that concept. And it worked like a charm, they cranked out six massively successful games before id/Bethesda decided it was time to reboot the Doom franchise 2016.
Perhaps it was payback for them to give Doomguy the Crucible in the reboot games (which looks a lot like the energy sword from Halo), but I can’t help but think these two are essentially the same character.
Halo reach came out way later, and doesn’t look half as good as master chief but that’s not due to the coloring and instead the worse looking armour