Mouse was a operative working for the Rebel Alliance, and he belonged to the Duros species.
Acting as a demolition and sabotage expert, Mouse participated in the infiltration of the Imperial base on Kalist VI alongside Luke Skywalker, Basso, Able, Deena Shan, and a number of other Rebels, eight months following the Battle of Yavin. It was also noted that he possessed a keen and subtle sense of humor.
As the mission neared its end, Mouse received the task of setting up explosives to create a distraction. However, while in the process of placing these explosives, he was detected by Imperial soldiers. They grew wary of his behavior and his vocalizations, demanding that he remove his helmet. Mouse complied, and as the perplexed troopers gazed at him, he charged through their formation and fled into the maintenance tunnels. The Imperials quickly located him and fatally shot him, but they were unable to prevent him from activating some of the diversionary explosives. This act was crucial in ensuring the success of his fellow Rebels' mission.
Hasbro created an action figure of Mouse in 2008 as part of their Expanded Universe Comics series.