A person who's saved the galaxy is a rare find, but as fate would have it, two such individuals from very different galaxies will meet when the Normandy SR-2 finds a faint distress beacon.

Master Chief and Cortana crash land on an unknown planet in an unknown time, where they are discovered by Commander Shepard and her crew. Yet again Master Chief is thrown into a battle that spans the entire galaxy.

When something is activated on the ark before it's destruction the Hero's of the halo universe are sent into the universe mass effect. But there not alone in its activation it seems that more than just good came from the other side. Will they survive...

Just Imagine the Master Chief in the Mass Effect universe, that pretty much explains it.

What if we knew about the protheans sense the fiftys. What if that prompted us into a different course of action that would take a peice of humanity and thrust it in a drastically different direction. This is the result. xover w halo and others

An uber-hacking Master Chief bullies Shepard off the scene and saves the galaxy by himself from the Reapers. Or at least, he tries to!

when sheperd uses the J relay, he finds that the alince isn't the only humans around. when sheperd teams with Peti-oficer/Sparten Brock Maran, they find a prothein becon, but the covanent and geth have teamd to gether after they create a new relay to halo

The Ninth Age of Reclamation is over. The Covenant, along with its member state of the Alliance serving Humanity, have become a part of Citadel space. A special operations soldier, Shepard, will find herself thrust forward into an epic race against time.

The Wall cascades, as two inquisitive Humanities tamper with that which they should not. And in the hollow space between universes, like a rats in the walls of a house that they build themselves, entities watch. Halo/Mass Effect