Heterosaccus is a genus of barnacles in infraclass Rhizocephala.

Like other taxa in this group, they parasitize crabs.

Geoffroy Smith circumscribed the genus in 1906; he initially only included H. hians.

Smith circumscribed a genus distinct from Sacculina due to a difference of the mesentery; in Heterosaccus, the mesentery does not stretch down to the mantle opening but rather only is present on the ring of attachment.

[1] As of 2017[update], WoRMS recognizes the following fifteen species.