In forgotten ages past, two near eldritch forces vied for the very life essence of the Galaxy. Unknown to the young races, that war is still ongoing. how can the UNSC, the Citadel Council or the Covenant hope to stand against such forces, when they are still embroiled in their own petty squabbling? How could they hope to survive the War of the Old Ones?

When someone contacts the Quarians about old machinery, they should think twice before engaging with a strange yet so familiar species, a war, and circumstances that will shock two galaxies now that the rift is open.

This is a Mass Effect - Halo - XCOM Crossover. In the year 2084 during the Asteroid Belt Offensive XCOM Elite Unit Strike-1 discovers an Ethereal Station but must Psionic Teleport away but something goes wrong. In the Year 2552 the UNSC Fearless an Orion-Class Assault Carrier is forced to escape Reach under heavy fire, during the Slipsapce Transit something goes wrong.

Xen is the gateway between universes and dimensions. It is the place where time, space, physics, and other known rules that define ones life go out the metaphorical window. What will happen when a Child of Xen, a perfect Supersoldier, a Guardian of Humanity, and a Spectre of a Council of aliens find themselves caught up in a war of survival? Find out in "Xen Effect".

The reapers brings new galactic superpowers into the war after invading the Orion arm of the galaxy. will the conflict unite them against a common foe or will they open conflict with each other.

ODST Captain Nathanial Renkov unintentionally becomes the first Helljumper to survive being dropped through a Slipspace anomaly. The problem? He has no idea where is and is surrounded by aliens the UNSC has no record of. Even worse? No one knows what the UNSC is. Follow his story as he tries to make sense of his new surroundings while trying to survive a new galactic threat.

AU. Spartans never die. But we all know that's not true. A terrifying new enemy approaches and only time will tell if the forces that be can stop them.

A UNSC Human-covenant war-era battle group led by a Punic class supercarrier is introduced to a new galaxy. One where people are xenophilic, use to times of peace and harmony, and against disrupting the Status Quo. What will an extremely aggressive xenophobic and battle-hardened human faction add to the mix? and will their addition change the future of this galaxy. (No Spartans)

When the Long Night of Solace is evaporated over Reach via the weaponized usage of a Slipspace Drive, it ferries with it in its swallowed sections the Covenant Empire and, more horrifyingly, the desperate measures that the UNSC used to fight them. When they are found in a universe on the precipice of their own history, the meaning of the term "Mass Effect" will change forever.

Emile survives the two zealots at the end of Reach, and after surviving Covenant onslaught, finds himself in the ME universe. Kick-ass picture is thanks to freejimmy on deviantart

A Citadel Exploration fleet filled with people the council didnt want around discovers something that will change the face of Citadel Space forever. The council will experience a crash course in the fight for survival (Reaper Incursion Arc)

Master Chief wakes up in the Mass Effect universe and joins Commander Shepard in an effort to stop the Reapers. With time running out, can they stop the extinction of every species, or will they fade into legend?First, they got to stop the Reapers though...

In the vast multiverse events can happen that should never happen this is the story of one such event in a a universe that was should never have been.

The knowledge of sin is the beginning of salvation. More than 40 years after the end of the war against the Covenant, a new storm is brewing on the edge of the human empire. Will the colonies of the Linwood Sector be able to withstand this new threat or will they burn like Harvest once did?

There was more on the line... Yet plans and webs were made. Rated T for violence, death, and profanity.

Noble Six was alone after the death of Emile. The Pillar of Autumn had left Reach, leaving the lone Spartan behind. But what if instead of dying on Reach, fighting to his last breath, Six survived? What if he escaped Reach and headed for Earth, only to end up in another galaxy, in another war? Will he agree to fight the reapers alongside aliens? Find out in Noble Effect

Commander Shepard and his team have gathered together the races of their Galaxy in an effort to defeat the Reapers. But is it enough? When the team comes across a strange woman they find out that if they are to truly defeat the Reapers once and for all. They will need all the help they can get. But not from their Universe. Multiverse Crossover! Chapters 6-22 Being Rewritten!

Ce qui ne devait être qu'une simple mission de récupération, pour la commandante Shepard de l'UNSC, a rapidement tourné au cauchemar. Désormais, l'humanité et la citadelle sont au bord de la guerre, inconscient qu'un danger bien plus grand les guette. Deux Shepard ne seront pas de trop pour cette mission.

A joint Asari-Turian operation salvaged a "package" from a derelict wreckage in the Terminus Systems, whereupon they release a force of war beyond their reckoning. Hoping to avoid another war, Commander Shepard recruits the "package" into her team. A simple act of kindness, unwittingly paving the way for a clash unlike the galaxy has ever seen. Fate directs the flames of war.

After the Great War Humanity was a different creature. Their brush with extinction left them cold and vengeful, and so they sought revenge for the transgressions of the Covenant species. With their eradication Humanity, driven by xenophobia, took their position as the unrivalled power in the galaxy. However, will a xenophilic alien federation, in a new galaxy, change their outlook?

Through ONI's manipulation, the UNSC stumbles upon a Mass Relay and is dragged into a new war. They'll discover the battered races of the Citadel, the political intrigue of its factions, and a second group of humans governed by the Systems Alliance, divided by Cerberus, and lead by Commander Shepard. Yet no one can stop what is to come: the Reclamation, and the death of the galaxy.

For eons past, they enjoyed the harvest of their farms. Countless civilizations breathed life because they allowed it. Now, they will die because he demands it. Halo/Mass Effect but with heavy elements from Warhammer 40k. M-Shep/Miranda, OC/Liara. HFY

An escape from an overrun galaxy lands them in another galaxy? What does being the biggest fish in the water gain you in a world without heavy hitters? Rated T for violence, death, and profanity.

Six's life was a giant war. Every battle was a test of sheer tenacity and stubbornness against insurmountable odds. Every moment, every bullet fired, every Covenant, Insurrectionist, and Flood spore killed has led up to his last fight. Once again he was one of the few that stood between Earth and her enemies. This would be his final battle, and nothing could change that, right?

We thought ourselves powerful, able to conquer a galaxy with nothing but toys. When we overcame every challenge, breached the space between the galaxies themselves, what use were the words of a race ashamed of their own past? Yet we cannot deny that we were warned, for while a challenge to a human is laughable, a challenge to humanity is a death sentence.