Sitsqwayk is a genus of baleen whale from Late Oligocene (Chattian) marine deposits in Washington state.

The generic name refers to a powerful water spirit in the folklore of the Klallam that is said to bring wealth.

[1] Sitsqwayk is distinguished from other early chaeomysticetes by the features of the rostrum and skull roof, especially in the premaxillae.

[1] Within Chaeomysticeti, Sitsqwayk is recovered as the most basal chaeomysticete, more primitive than eomysticetids and Horopeta.

[1] Sitsqwayk is coeval with another Oligocene mysticete from the Pysht Formation, the aetiocetid Fucaia goedertorum.