Tosh was the herd-mother of a rancor tribe that belonged to the Singing Mountain Clan on Dathomir. According to a New Republic Intelligence report, Tosh was the largest and oldest rancor ever cataloged. She was the mother of Dhum and Ichor, who was killed in battle against the Nightsisters.
Tosh was very capable on the battlefield, aiding the Singing Mountain Clan using varied primitive weapons. In one instance, after seeing an Imperial walker murder her daughter Ichor, she went on a rampage, completely smashing several walkers and then stomping on a Nightsister who threatened Luke Skywalker. She was capable of scaling steep cliffs and crossing large crevasses effectively while carrying both passengers and heavy cargo.
- The Courtship of Princess Leia (First appearance)