Stilgar is
Naib of
Sietch Tabr, on
Arrakis, also known as
Dune. He is a traditional desert
Fremen, a man who commands much respect. He finds
Paul Atreides and the
Lady Jessica in the desert, and after a brief struggle, allows the two of them to accompany his
tribe to Sietch Tabr, which includes
Chani, Paul's future lover and
concubine.
The Lady Jessica misjudges Stilgar as nothing more than a savage, but finds that he has strong conviction, a man of careful inner balances.
Stilgar realizes that as Paul Atreides becomes Muad'Dib after defeating Jamis, that maybe the Bene Gesserit-planted prophecies (but Stilgar doesn't know they're planted prophecies) are true - that Paul-Muad'Dib may be the Lisan Al'Gaib, the Fremen messiah. Stilgar eventually acknowledges the face that the mythos and personal power of Muad'Dib, including his prescience, are going to overwhelm his own personal power, where in Fremen tradition, a Naib is a person who is never to be taken alive. The truth of the matter is, in a Fremen tribe, it is tradition that for a person to become leader of a sietch, one must kill the present leader in a crysknife fight.
Stilgar chooses to bow down to Muad'Dib's wishes, as he is technically Duke of the Atreides, and thus, the legal owner of the planet Arrakis.
In the first book, Stilgar is a very deep, very internally balanced character. He plays pivotal roles as Muad'Dib's second in command. In Dune Messiah, and Children of Dune, his importance lessens and lessens.