Human, Covenant, Citadel, and non Citadel was united under single banner to face biggest galactic threats which threatening their very existence. Shepard was proceed to save entire of galaxy. (Read codex's first, please)

Thirty-five years have past since the end of the Human-Covenant War. Having reclaimed most all its previous glory, the UNSC exploration locates a massive artificial construct in the outer orbit of a star. While investigating the object alongside their Sangheili allies, new aliens come forth from the construct and bring humanity into a fate they never expected. ON HIATUS

When the four great races rise up to reclaim what was lost after the Great Cataclysm. How will the Citadel Counsel react. (Its an idea that just will not leave me alone. Is Teen for now may change in the future or maybe not at all.) Up for Adoption

Avenging the past leaves you with nothing, a Character from Mass Effects learns the hard way that there are worlds worse then the one they started in. One Shot, World Building

Masterchief wakes up after his long cryo sleep only to learn that everything he once fought for is now history. UNSC, Covenant everything. Can he once again become the humanity's greatest hero or someone else will carry his legacy?

When you become an extragalactic entity, meeting other galactic civilizations becomes an inevitable occurrence, and First Contact rarely goes well for the less-advanced society. Pre-ME through ME3. Rated T for language and implied sexual situations later on. Extremely Light parody on Halo OPness AKA Halo tech taken to its logical conclusion.

Fleeing from their universe, the reaper defector Enigma and his allies stumble into a new conflict. A conflict where the victim is out numbered and faced with extinction. The white reaper is not about to sit on the sidelines and watch this time... *Please read 'Mass Effect: The reaper Enigma' before reading this to reduce confusion.*

After a long deserved rest, the Master Chief awakens in a whole new galaxy.

A turian fleet stumbles on a human colony in the wake of the Covenant War. What will ensue?

Following the Human-Covenant War, Humanity finds a buried device that allows trans-galactic travel far faster than Slipspace. It was heralded as the greatest scientific find in Human history; the rest of the galaxy simply calls it the Mass Effect. Now mankind needs to forge a new place for itself among the stars.

"We fought, we bled, we died for our inheritance. We were Gods, and we were finally ready to pass down our Mantle. Then we were betrayed, vanquished from the stars and blotted from history. We have learned from our mistakes. We understand why the Precursors did what they did. We are the Reclaimers, and we will ensure that you face true retribution for your actions." ABANDONED

A Spartan team is a formidable fighting force. They can turn the tide in battles, stop invasions, save entire planets. But in a new universe, against a new enemy, their strength and prowess may not be enough...

A Batarian Pirate fleet stumbles upon a dorment relay in a previously unknown system. What's more interesting is that they find a world made of glass. Let's see what unfolds next.

As the UNSC is nearing defeat at the hands of the Covenant, the Allies intervene to prevent the Council from potentially gaining a new ally, and avert the need for another total galactic war.

John had always known what he could do, if given a challenge. He'd known his capabilities ever since he'd been a child, let alone a SPARTAN. But now, after surviving a trip he honestly shouldn't have, he's stuck on a planet with no orders, no manual, and no amount of training that could've prepared him for the situation he's now faced with... a Mindoir farm girl named Shepard.

In his death throes, Noble-6, the last of his team of advanced SPARTAN-IIIs, does the unthinkable. He touches Cortana's undelivered AI core at the center, blacking him out. when he awakens, he is aboard an unknown ship with his teammates and a cast of strange characters. Adventure awaits at every corner, picking up new-found friends on the way.

A strange tuning fork shaped artifact has discovered on the far reaches of the System Alliance's space... ...But there have been whispers of colonies disappearing... THE FLOOD IS COMING... This is ME in a Halo universe

ABANDONED! too much plot hole and suck plot. v2 on progress

this is a au story 1 the kig-yar open a star sling shot and the Galaxy is flip up side down and soon the universe will follow

Mistakes are a universal constant, they are made constantly by every race that has ever been known. But mistakes made by a single Batarian ship and the Turians in pursuit of it, will have far more reaching consequences than most. Halo/Mass Effect Crossover, AU

One hundred years after the Reaper's harvest, the remaining inhabitants of the galaxy are running for their lives and searching for a new home. When a lone vessel enters an area denied to the Reaper's harvest, they make contact with a race that could end the cycle for all time and return the galaxy to its former glory. Rated M for language.

In the ages of humanity there has been three generations. The first two were destroyed by the reapers. Now one young member of the Orbital Drop Shock Troopers will try to stop it happening again. His people are gone but he will keep fighting to save the , Third Generation.

The Covenant has assimilated humanity into it's ranks, and now they stand on equal footing with the sangheili. A CCS-class battlecruiser is exploring the Perseus Arm of the galaxy when it encounters a new race who call themselves "Turians".

.cancer

While Humanity and Covenant are enjoying their peace, the Sangheili colony of Axiom Prime finds itself under attack by a mysterious new race. The UNSC and Covenant are quick to respond, but why is the Master Chief deployed? What happened 30 years ago, when Chief decided to stop being the machine? And how exactly will a lone survivor cope with loss?