Cetus

Cetus (the whale) is the fourth largest of the 88 modern constellations, and was also one of the 48 constellations listed by Ptolemy. Despite its usual translation as "the whale", Cetus is often assumed to represent the sea monster menacing Andromeda.

Cetus contains the famous variable star Mira (Omicron Ceti), and also the nearby star Tau Ceti.