Akuze

Akuze is a planet that features in the Sole Survivor background for Commander Shepard. It is also mentioned in the assignment UNC: Dead Scientists.

In 2177, Akuze was in the early stages of colonization by humans when all contact was lost with the pioneer team. The Alliance sent in a Marine unit to investigate and look for survivors. When the unit camped for the night, they found themselves set upon by thresher maws. The Marines had no idea what they were facing and almost the entire unit was slaughtered. 50 Marines died.

If Shepard has the Sole Survivor background, the commander was the only known Marine to make it out of Akuze alive, though it isn't known how Shepard managed to survive. If Shepard meets Officer Eddie Lang on the Citadel with this background, Lang will comment on a monument at Akuze and an entire section dedicated to Commander Shepard, suggesting that the colony of Akuze survived the thresher maw massacre, or at least that a new one was established in its place.

Shepard can later discover that there was another survivor, Corporal Toombs, who claims the slaughter at Akuze was not an accident. According to Toombs, the renegade black ops group Cerberus deliberately set the thresher maws on the marines, to study the creatures and see how the unit reacted.

Mass Effect 2
If Commander Shepard has the Sole Survivor background, there is a news announcement about a Shepard Memorial being erected on Akuze and, that once the site is cleared of thresher maws, a commemoration ceremony hosted by Admiral Steven Hackett in 2186.