The fossil species Gallotia auaritae was described as a subspecies of Gallotia simonyi by Mateo et al. (2001). It has subsequently been widely accepted as a full species following Alfaro and Mateo (2003), although Cruzado-Caballero et al. (2019) note that no detailed formal justification for this has been provided.

This species is endemic to Europe, where it is restricted to El Hierro Island, Spain. It is assessed as Vulnerable (VU D1) on the basis that the most recent (2009) population estimate for this species indicates that the population contains around 300-400 individuals. There are no data on age distribution, but should research suggest that fewer than 250 of these are mature adults the species will warrant immediate uplisting to Endangered applying Criterion D. Additionally, it has an extent of occurrence of approximately 65 km² and occurs as a severely fragmented population. No continuing decline has been reported in any of the number of mature individuals, extent of occurrence, area of occupancy, the number of locations or subpopulations, or the extent and quality of the lizard's habitat, however, this coud be due to a lack of monitoring in recent years. Following cessation of feral predator control, a continuing decline in the number of mature individuals is possible. Should this be confirmed, or impacts from landslides be found to represent an ongoing decline in the extent and quality of its habitat, it will warrant listing as Critically Endangered applying Criterion B1.

This species is endemic to the island of El Hierro in the Canary Islands (Spain). Subfossil remains suggest that this species was once common in coastal areas (Mateo 2020) across the island. Naturalists' reports from the 19^th Century indicate that by this point large lizards were already restricted to rocky areas (Mateo 2020). The species was once present throughout much of the island and on the small offshore Roque Chico de Salmor, from which it was lost in the 1930s and to which it has been successfully reintroduced (M.A. Carretero pers. comm. October 2022). The species is currently restricted on the main island to the southern end of the Risco de Tibataje on El Hierro, in la Fuga de Gorreta, located between Guinea and Paso del Pino (an area of about four hectares). Reintroductions were planned or implemented at El Julan and la Dehesa on El Hierro, although its continued survival at these two sites is uncertain, and it is unclear whether the planned reintroduction to la Dehesa went ahead  (M.A. Carretero pers. comm. October 2022). The species ranges between 350 and 500 m asl.

The previous Red List assessment of this species (Mateo-Miras et al. 2009) gave the population size of this species as about 300 to 400 animals in the wild, including reintroduced subpopulations (Mateo-Miras et al. 2009). No more recent data are available and so these figures are used again in this assessment. Population trends are unknown, but since control of feral cats ceased in 2002 it is possible that declines are ongoing (Mateo-Miras et al. 2009). There has been no real monitoring of this species during the last 15 years (M.A. Carretero pers. comm. October 2022). There is evidence of stability in the reintroduced Roque Chico de Salmor subpopulation, but there is no evidence of survival of the subpopulations reintroduced on the main island and confirmation of the persistence of lizards here is required.

It is now confined to small areas of cliff with sparse vegetation. The species is believed to have once occurred throughout much of El Hierro, being only absent from areas of laurel forest.

It is a largely herbivorous species and has two clutches of 5–13 eggs.

The major threat to this species is predation by feral cats, and possibly also by dogs and rats. A remnant subpopulation was extirpated from the Roque Chico de Salmor in the 1930s through the overcollection of animals primarily due to a brief European collecting craze for the animals (Mateo 2020). Control of feral cats stopped in 2002. This species is confined to an "extremely narrow range" on steep slopes where it is at risk from landslides, and the frequency of landslides is likely to increase with extreme climatic events (Henle et al. 2008).

This species was the subject of an early 20^th Century collecting craze (detailed by Mateo 2020), but no current use or trade appears to exist.

The species has been the focus of two EU LIFE projects: "Programme for the restoration of Hierro giant lizard Gallotia simonyi" (LIFE94 NAT/E/001238); and "Reintroduction of El Hierro giant Lizard in its former natural habitat" (LIFE97 NAT/E/00419).

A recovery plan for this species has been developed, and captive-breeding and reintroduction programmes are in place. The species was successfully reintroduced to the Roque Chico de Salmor in 1999. The success of subsequent reintroductions at El Julan and la Dehesa is in need of confirmation.

Continued control of feral cats should be resumed to allow population recovery. This species is protected by national and international legislation. It is listed on Appendix I of CITES. Both la Fuga de Gorreta and the Roque Chico de Salmor are protected areas.