Perseus is a prominent northern constellation, one of Ptolemy's forty-eight, named for the Greek hero who slew the Gorgon Medusa and rescued the princess Andromeda from the sea-monster. It lies amid the figures of that myth, Andromeda, her parents Cepheus and Cassiopeia, and the monster Cetus, so that the whole story is written across this quarter of the sky. Its second-brightest star, Algol, the Demon Star, marks the head of Medusa and is a famous eclipsing variable whose regular dimming was noticed in antiquity and gave it its ominous reputation. The constellation also hosts the radiant of the Perseid meteor shower. These are the features of Perseus as the classical and modern astronomical traditions describe it, distinct from the zodiac; the constellation is a star pattern, not an astrological sign.
The giraffe constellation Camelopardalis, immediately north of Perseus, has no ancient pedigree at all; it was introduced only in the early seventeenth century, credited to the Dutch cartographer Petrus Plancius and popularised by Jakob Bartsch in 1624, filling a large, genuinely faint gap between Perseus, the two Bears and Cassiopeia that the Ptolemaic tradition had simply left blank.