Wallyum Rudderwake was the male otter leader of Holt Rudderwake. He was the husband of Dorumee, and the father of Inbar Trueflight and Winniegold. He was a healer for the seal Hawm and his tribe; the otters and seals were allies as a result, and Wallyum and Inbar learned to speak their language. The seals called the otter chieftain "Waaaaylum", not being able to properly pronounce his name.
Martin the Warrior appeared to Wallyum in a dream, asking him to assist Redwallers in defeating Ublaz Mad Eyes. Wallyum was more than willing to comply; he provisioned and fed the Redwallers on his island and and allowed his son Inbar to accompany Martin II, Clecky, Viola Bankvole, Plogg, Welko, and Grath Longfletch on their journey to Sampetra to save Abbot Durral. He also used his knowledge of the seal language to convince Hawm's tribe to accompany the warriors and tow their raft; this later saved Welko and Viola's lives, as the seals took care of many vermin who pursued the duo.