Stenocercus guentheri, also known commonly as Günther's whorltail iguana and la guagsa de Günther in South American Spanish, is a species of lizard in the family Tropiduridae.

The species is native to northwestern South America.

[2] The specific name, guentheri, is in honor of German-British herpetologist Albert Günther.

[1][2] The preferred natural habitat of S. guentheri is shrubland, at altitudes of 1,230–3,700 m (4,040–12,140 ft), but it has also been found in gardens, plantations, pastures, and urban areas.

[1] S. guentheri is oviparous,[1][2] and may provide some parental care.