[2] It is located near several other constellations named after ancient Greek legends surrounding Perseus, including Andromeda to the west and Cassiopeia to the north.

Perseus is also bordered by Aries and Taurus to the south, Auriga to the east, Camelopardalis to the north, and Triangulum to the west.

The galactic plane of the Milky Way passes through Perseus, whose brightest star is the yellow-white supergiant Alpha Persei (also called Mirfak), which shines at magnitude 1.79.

The best-known star, however, is Algol (Beta Persei), linked with ominous legends because of its variability, which is noticeable to the naked eye.

In Greek mythology, Perseus was the son of Danaë, who was sent by King Polydectes to bring the head of Medusa the Gorgon—whose visage caused all who gazed upon her to turn to stone.

Incorporating stars from the northern part of the constellation, it contained Mu, Delta, Psi, Alpha, Gamma and Eta Persei.

The pile of corpses prior to their interment was represented by Jīshī (積屍, Pi Persei), the sixth paranatellon of the house.

In Polynesia, Perseus was not commonly recognized as a separate constellation; the only people that named it were those of the Society Islands, who called it Faa-iti, meaning "Little Valley".

[13] Perseus is bordered by Aries and Taurus to the south, Auriga to the east, Camelopardalis and Cassiopeia to the north, and Andromeda and Triangulum to the west.

[15] Algol (from the Arabic رأس الغول Ra's al-Ghul, which means The Demon's Head), also known by its Bayer designation Beta Persei, is the best-known star in Perseus.

[18] These two are separated by only 0.05 astronomical units (AU)—five percent of the distance between the Earth and Sun; the main dip in brightness arises when the larger fainter companion passes in front of the hotter brighter primary.

AG Persei is another Algol variable in Perseus, whose primary component is a B-type main sequence star with an apparent magnitude of 6.69.

[23] With the historical name Mirfak (Arabic for elbow) or Algenib, Alpha Persei is the brightest star of this constellation with an apparent magnitude of 1.79.

[32] Of magnitude 4.05, nearby Iota Persei has been considered a member of the group, but is actually located a mere 34 light-years distant.

[37] Once thought to be a member of the Perseus OB2 Association,[38] Omicron Persei (Atik[39]) is a multiple star system with a combined visual magnitude of 3.85.

[40] It is composed of two blue-white stars—a giant of spectral class B1.5 and main sequence star of B3—which orbit each other every 4.5 days and are distorted into ovoids due to their small separation.

At an estimated distance of 1,475 light-years from Earth, the system is now thought to lie too far from the center of the Zeta Persei group to belong to it.

One component is a red dwarf star of spectral type M4.5V,[42] which orbits a mysterious dense and heavy object—possibly a black hole—every 5.1 hours.

Discovered on 21 February 1901 by Scottish amateur astronomer Thomas David Anderson, it peaked at magnitude 0.2—almost as bright as Capella and Vega.

[51] Named Gorgonea Tertia, Rho Persei varies in brightness like Algol, but is a pulsating rather than eclipsing star.

[52] It is a semiregular variable star of the Mu Cephei type, whose apparent magnitude varies between 3.3 and 4.0[53] with periods of 50, 120 and 250 days.

[54] The Double Cluster contains three even larger stars, each over 700 solar radii:[55] S, RS, and SU Persei are all semiregular pulsating M-type supergiants.

V718 Persei is a star in the young open cluster IC 348 that appears to be periodically eclipsed by a giant planet every 4.7 years.

[78] It is very difficult to observe visually because its low surface brightness makes it appear dimmer than most other emission nebulae.

Its jets, caused by the supermassive black hole at its center, extend several million light-years in opposing directions, making them some of the largest objects in the universe.

[88] The Perseids are a prominent annual meteor shower that appear to radiate from Perseus from mid-July, peaking in activity between 9 and 14 August each year.

[89] The September Epsilon Perseids, discovered in 2012, are a meteor shower with an unknown parent body in the Oort cloud.