Polygonus, with Telegonus, was a son of Proteus. The pair rashly challenged Heracles to a wrestling match in which they were killed. Polygonus' name means 'having many children', from polys, 'many' and gonos, 'child' (as for Antigone).

This must have been a propitious name, since we are not told of Polygonus having any children (or even of his marrying), and Proteus was not known to have been a prolific father.