Short answers, pulled from the story.
Perseus was the legendary founder of Mycenae and the Perseid dynasty. He was the son of Zeus and the mortal Danaë, and stood alongside Cadmus and Bellerophon as the greatest Greek heroes before Heracles. He is best known for beheading the Gorgon Medusa and rescuing Andromeda from the sea monster Cetus.
Perseus used a polished shield lent to him by Athena to see Medusa's reflection without being turned to stone. He walked backward into the cave on the Island of Sarpedon where the Gorgons slept, and beheaded Medusa with the harpe sword lent to him by Hermes. Athena guided the blade.
Perseus carried winged sandals and the harpe sword from Hermes, the helm of invisibility from Hades, Athena's polished shield for viewing Medusa's reflection, and a kibisis, a special knapsack from Athena to safely carry the severed head. The gods supplied all of these before he set out.
The Oracle at Delphi warned King Acrisius of Argos that he would be killed by his own grandson. Despite imprisoning his daughter Danaë to prevent her bearing children, Perseus was born and eventually fulfilled the prophecy. According to Pausanias, Perseus accidentally struck Acrisius with a quoit during athletic games at Larissa, killing him.
The ancient Greeks considered Perseus a genuine historical figure and credited him with founding Mycenae. Pausanias recorded a shrine to Perseus on the road from Mycenae to Argos and a sacred fountain there called Persea. Apollodorus added that Perseus fortified Mycenae and the nearby settlement of Midea, though Apollodorus acknowledged this was conjecture.
The constellation Perseus was cataloged in the 2nd century by the Greek astronomer Ptolemy. It contains the famous variable star Algol, the deep sky objects Messier 34, the Double Cluster, the California Nebula, and the Little Dumbbell Nebula (Messier 76), along with eight named stars. The constellation gives its name to the Perseid Meteor Shower.