Probably just a spartan with the same sort of gear.
Although, while we're on the subject the one on the left looks a bit like an elite (He's obviously not though) he's probably some sort of heavy.
The one on the right of him looks like a young spartan, probably the spartan equivelent age of 18.
The middle guy looks like The Chief or any other generic spartan.
By the one on the right of him stands, I'd say it was a female spartan.
The one crouching on the right is obviously a sniper.