Man, one of us really needs to write up a blurb we can just copy-paste when a question like this comes along.
Basically, the Mega-Verse is a group of interconnected comics by multiple users, set in a (mostly) canon-adjacent version of the Halo universe - this basically mean that we mostly acknowledge the broad strokes of Halo canon, but our stories sometimes diverge in places. For example, some of us have featured Atriox in our comics, even though he's still on the Ark at the point in canon our stories take place.
The Mega-Verse was founded by Admiral-Sabree, and some of the main collaborators include myself, CharlieBucket, GreenSpartan082, and a bunch of others (side note: we really need to put together a proper list of users and comics who've contributed to the Mega-Verse). Some users have created small one-off comics that are set in the Mega-Verse, or created comics that are set in alternate universes, and feature re-imagined versions of characters or events from the Mega-Verse.
This particular thread is where we've been very slack in listing the characters from our comics. The main Mega-Verse thread, which we use to conduct our planning and collaboration, can be found here:
https://www.megaconstrux.com/en-us/comm ... =24&t=3785