Leptothyra is a genus of sea snails, marine gastropod mollusks in the family Colloniidae.

This genus was previously placed in the family Turbinidae.

The name Leptothyra is generally attributed to Pease (1869), and the name "Leptothyra Pease, 1869" is usually treated as a valid name for small colloniines. Although Leptothyra is a junior objective synonym of Homalopoma, the species usually treated as valid in that genus are provisionally listed in WoRMS under "Leptothyra sensu Pease, 1869", pending a taxonomic/nomenclatural reappraisal.

Leptothyra J. G. Cooper, 1867 is now considered a junior objective synonym of the genus Homalopoma Carpenter, 1864.

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