Log-a-Log Groo of the Guosim was a shrew from Mossflower Woods. He frequently visited Redwall Abbey with his tribe and was good friends with Skipper.
Groo helped search for the Dibbuns Ruggum and Bikkle, and helped escort them safely back to the Abbey after the pair had fled from what they claimed was a monster and become lost in a storm. Groo was also one of the searchers for Brockhall after Ruggum and Bikkle told of their discovery of the ancient edifice. Later, he helped defend the other searchers against a flock of crows that attacked them, and escorted the party safely back to the Abbey without finding Brockhall again. When Malbun Grimp and Crikulus attempted to return to the crow territory at night to safely search again, they too were chased by the "monster" and were kidnapped by Wicky's Band. Groo was a member of the search party that rescued the two oldbeasts, and he and Skipper decided to do some searching to figure out what the "monster" was. After a second encounter with the stoats, Groo and Skipper discovered what had been haunting Brockhall all this time - a trio of adder siblings who moved like a three-headed beast. Groo was scared of snakes like most shrews, and told a reluctant Skipper to flee, and the pair narrowly escaped with their lives.
After the three serpents were determined to be a menace to the woodlanders, Groo kept his tribe at Redwall for a time. He took an intense dislike to Bluddbeak meeting him for the first time, but later admitted that he died a hero.
After helping the Redwallers in the fight against the Freebooters and Ratguards, Groo and his tribe retired back into Mossflower, once the serpents had all been slain.