In Greek mythology, Dicaeus or Dikaios () was a son of Poseidon and brother was Syleus. They lived near the Mountain Pelion in Thessaly.
Dicaeus hosted Herakles. Unlike Syleus, who was killed by Herakles, Dicaeus was a just man, which was suggested by the very literal meaning of his name (ÃÂïúñùÿà= Just).
The Dicaea city in Thrace was named after him.