Several, see text Thereus is a genus of gossamer-winged butterflies (family Lycaenidae).

These small butterflies occur essentially all over the Neotropics.

[1] Though this genus was first proposed long ago, for much of the time Thereus was included in the "wastebin genus" Thecla.

In recent times, it has been proposed to remove several species from Thereus to smaller or even monotypic genera.

[1] The junior synonyms of Thereus are thus:[1] The following named species are placed in Thereus at present:[1] In addition, a number of as yet undescribed butterflies are suspected to belong here too:[1]