Rhantus is a genus of beetle in family Dytiscidae. There are about 100 species distributed worldwide. They often live in pools and marshy habitat types. Several species have colonized oceanic islands and become endemics.

This genus is paraphyletic and will likely be revised, redefined, and split into several groups in future studies. As a result of research published in 2017 by Balke et al., 17 species were moved from Rhantus to the genera Nartus, Meridiorhantus, Caperhantus, and Carabdytes.

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