The blue iguana or Grand Cayman iguana (Cyclura lewisi) is an endangered species of lizard of the genus Cyclura endemic to the island of Grand Cayman.
The blue iguana is one of the longest-living species of lizard (possibly up to 69 years). The record is 67 years.
The blue iguana prefers dwelling in rocky, sunlit, open areas in dry forests or near the shore, as the females must dig holes in the sand to lay eggs in June and July. A possible second clutch is laid in September. The blue iguana's vegetarian diet includes plants, fruits, and flowers. Its coloration is tan to gray with a bluish cast that is more pronounced during the breeding season and more so in males. It is large and heavy-bodied with a dorsal crest of short spines running from the base of the neck to the end of the tail.