Lobatus gigas, commonly known as the queen conch, is a species of large edible sea snail, a marine gastropod mollusc in the family of true conches, the Strombidae. This species is one of the largest molluscs native to the Tropical Northwestern Atlantic, from Bermuda to Brazil, reaching up to 35.2 cm (13.9 in) in shell length.

The queen conch is herbivorous and lives in seagrass beds, although the exact habitat varies during the different stages of its development. The adult animal has a very large, solid and heavy shell, with knob-like spines on the shoulder, a flared thick outer lip and a characteristic pink-coloured aperture (opening). The flared lip is completely absent in younger specimens. The external anatomy of the soft parts of L. gigas is similar to that of other snails in the same family: it has a long snout, two eyestalks with well-developed eyes and additional sensory tentacles, a strong foot and a corneous sickle-shaped operculum.

The shell and soft parts of living Lobatus gigas serve as a home to several different kinds of commensal animals, including slipper snails, porcelain crabs and cardinal fish. Its parasites include coccidians. The queen conch is hunted and eaten by several species of large predatory sea snails, and also by starfish, crustaceans and vertebrates (fish, sea turtles and humans). The meat of this sea snail is consumed by humans in a wide variety of dishes. The shell is sold as a souvenir and used as a decorative object. Historically, Native Americans and indigenous Caribbean peoples used parts of the shell to create various tools.