What is the name of the kindly Marsh-wiggle in The Silver Chair?

The kindly Marsh-wiggle in The Silver Chair is Puddleglum.

Puddleglum joins Eustace Scrubb and Jill Pole during their search for the missing Prince Rilian. He lives in the marshes on Narnia’s northern edge and becomes their guide as they travel toward the land of the giants. Though he constantly expects trouble, his pessimism often reflects practical judgment rather than cowardice.

Puddleglum proves especially important in Underland, where the travellers are held by the Lady of the Green Kirtle. He resists her attempt to make them forget Narnia and Aslan, eventually stamping out her enchanted fire despite badly burning his webbed foot. That act helps break the spell over the group and allows them to recognize the imprisoned young man as Rilian.

A common mix-up is assuming that every named Narnian creature is a major recurring character. Puddleglum is unusual: he is the only Marsh-wiggle in the series given a name and dialogue. C. S. Lewis reportedly modeled aspects of him on his gardener, Fred Paxford.