Flag depicting the dynastic Arms of the Vatatzis [Vatatzes] family. A prominent military family from Thrace, one of its members, John III Doukas Vatatzes, married into the Lascaris family and eventually became emperor of Nicaea in 1222.
Vert, a double-headed eagle displayed Or, above each head an estoile Argent.
Own work, Reference: Rietstap's Armorial [1]
W3C-validity not checked.