Grumm Trencher was a male mole from Noonvale. He was close friends with Rose and Brome and later, Martin the Warrior and Pallum, and was also the uncle of Bungo. Known for having a propensity to create various soups, Grumm always carried a ladle in his belt.
Grumm traveled with Rose to Fort Marshank in order to rescue Brome from the clutches of Badrang the Tyrant. Grumm's natural abilities for burrowing underground allowed him to create a tunnel underneath the Fort and rescue Martin the Warrior, Felldoh and Brome from the pit where they had been thrown. Although intended as a temporary device, Grumm's tunnel in the sand proved very solid and was used many times during the action around the Fort, by liberated slaves as well as by invading horderats. In the end, however, it was used as a trap against the vermin and became their own tomb.
Grumm was an excellent cook and was able to make a good meal out of any ingredients available. He considered meal preparation to be a very serious and important affair and could act as a general in charge of a mission in the gathering of food. Grumm also possessed a very healthy appetite and incurred Mildwort Mirdop's strong disapproval when he had the audacity of requesting a second scone for tea. His attraction to food sometimes led Grumm to unexpected trouble. He once disturbed a nest of particularly fierce bees as he was looking for water and had to be rescued from his predicament by Martin and Rose. When Rose was killed in the final battle at Marshank, Grumm was extremely grieved by her death and would later plant a rose, named for her, upon her grave.
- In medieval cuisine, a trencher was a stale piece of bread used for a plate.