Kladeos (Greek: Κλάδεος) or Kladeus, Latin: Cladeus or Cladeos was a river god in Greek mythology.

It is a river that flows from the north, through Olympia and empties into the Alpheus. The river in the winter is protected from the flooding of Ancient Olympia. In the Mycenaean period, the Kladeos flooded the area. The flood continued in the middle ages and went up to the German excavations of Olympia in 1875 where it buried Olympia with a height of 4 m.

The Greek poet Pindar in the 400s BC studied the intersection of Cladeus and Alpheus rivers.

Kladeos is also a community in the prefecture of Ilia.