Who’s seen this?
Right at the start of Winter on Legendary.
You exit the aircraft after Carter - now key ‘Sprint’ and jump over the first couple of ledges.
Look down towards the path that leads to the Moa and you’ll see something sprinting away.
It’s got Active Camo and is carrying what looks like a rifle.
I’ve managed to clip it with a few pistols shots and seen its screens flicker - but I’ve never managed to bring it down.
Any Doc Holliday’s out there got a First Strike on it?
Rather interesting it is a spec ops Sangheili holding a plasma repeater he also seems to have an armor glitch on his back.
I could not get him as he despawns around the corner.
Isn’t it a BOB, those special Gold Elites?
> Who’s seen this?
>
> Right at the start of Winter on Legendary.
> You exit the aircraft after Carter - now key ‘Sprint’ and jump over the first couple of ledges.
> Look down towards the path that leads to the Moa and you’ll see something sprinting away.
> It’s got Active Camo and is carrying what looks like a rifle.
> I’ve managed to clip it with a few pistols shots and seen its screens flicker - but I’ve never managed to bring it down.
>
> Any Doc Holliday’s out there got a First Strike on it?
It’s a BOB, only not the golden kind and only appears on the Legendary difficulty. If you kill it it drops a data pad which you can read. This has been known since launch day so I’m surprised you only just heard about it.
Yes you’ll find out about him in every Data Pad guide. 
(Finding all data pads it pretty cool btw, try it!) This one is not really a B.O.B… For instance, he will not count for the ‘kill-a-BOB’ daily challenges. This one is often called ‘Bill’.
I managed to assassinate him once. The trick is to A) Use your sprint as well as possible, B) Get a few good ‘Slide jumps’ C) Shoot his shield so that he staggers for a second (this doesn’t always happen, or not in the right way, so you need some luck as well).
Thanks for the replies!
I came late to Reach and didn’t bother about Data Pads - I think I’ve only picked up one.
But now that’s a new target to go for, and I’ll start by getting BILL!
It’s not chronologically the first one though! Iirc, it’s the first 9 on Easy-Heroic, and numbers 10-19 only on Legendary (so, this one is number 10). Not that the chronology matters much.