Ziaelas was King of Bithynia. He was the son of Nicomedes I and Ditizele. After Nicomedes I died, his second wife Etazeta became ruler on behalf of her infant sons. The grown-up Zialas had previously fled to Armenia. Now he returned, at the head of some Galatians. Although Etazeta was supported by neighbouring cities and Antigonus III Doson, Ziaelas conquered first part, then all of Bithynia.
Etazeta and her sons fled to Antigonus' court in Macedonia.
