This is universe 30 where the Mass Effect and Ben 10 Universes are fused

After Vilgax latest planed failed he and Ben where braught into the Mass Effect Universe. Ben allies himself with Shepard to stop Vilgax, and the Reaper

The Council held the illusion that they were the only alliances of races in galaxy, only for that illusion to be shattered when a Turian fleet encounters an alliance of species that could boast hundreds of species in it. (Basically what if the species of Ben 10 meets the species of Mass Effect)

After a cosmic bomb goes off and splits off copies of Ben into alternate realities, an older version of Ben lands on Eden Prime during Saren's attack. Using his shapeshifting abilities and advice from Paradox, Ben fashions himself as an extra-galactic ambassador. Joining Jane Shepard's crew, Ben finds himself on an(other) epic quest to determine the fate of the galaxy. Ben/Harem

An alternate Ben 10 becomes lost in the Mass Effect Universe after a run-in with one of his foes. After creating a name for himself on Omega, he draws the attention of a newly revived Shepard who seeks his help in her fight against the Reapers. How will the Omnitrix wielder's presence effect the fate everyone within the Mass Effect universe? Will it be all good? Some bad?

Four years after the Diagon was defeated, Ben receives an urgent mission from Professor Paradox and is sent to an alternate universe. However, things in this alternate universe are not what he is used to and he must learn to get used to it, especially over one important factor: his new teammates are all trained killers. BenXLiara, M!ShepXAshley.

Ben Tennyson is quite experienced in saving his own universe, but now Paradox has enlisted him to save another. He'll be going up against a terrorist organization, insect-like aliens, and a race of unstoppable, genocidal machines. But he won't be doing it alone.

On a mission from Paradox, Ben Tennyson has crossed over into another universe. Now, he must work alongside Commander Shepard in order to save the galaxy from extinction, first from the Collectors, then the Reapers. Ben/Miranda, MShep/Liara, Garrus/Tali. Based on Judge Royce's story. Discontinued. Remake is up!

Ben Tennyson has many female admirers, but none of them can compare to the ladies of this alternate reality. A series of one-shots pairing up our hero with Mass Effect girls.

Ben Tennyson has fought all kinds of criminals in his life as a hero, but when Paradox sends him to Omega to meet a group of people that he has no idea about, can he help these heroes fight these evil threats to mankind and possibly build a harem of the most beautiful women in the galaxy? That's a new one. Rewrite. Ben X Harem and other pairings are also included.

Ben Tennyson is sent on a mission to another galaxy by paradox to help a group lead by a person name commander Shepard save there galaxy from a machine race known as the reapers who are hell bent on there extermination can Ben and his new Friends save the galaxy or are they like all the the past cycles doomed from the start only time will tell.

Ben Tennyson has done many amazing and impossible things during his hero career. But saving an alternate reality from a race of genocidal machines? That's a new one.

Ben had recently turned 25, and nothing's the same anymore. Now Azimuth has given him a new Omnitrix and the Master Control. Thrown into a new Universe to save by Professor Paradox, Ben must face a new kind of battle, nothing he would have been able to prepare for, The reapers of the Mass Effect Universe. (Will end up a yaoi story for Ben, but undetermined pairings, M for future)

Shepard receives the unexpected help of two beings from another dimension. How will the arrival of the Tennysons affect the ME Universe? F-Shepard/Joker, Ben/Gwen