Paris Alexandros is the central antagonist of Homer's epic The Iliad, being responsible for the kidnapping of Helen of Troy and therefore the entire Trojan War indirectly.
Paris was the child of Priam and Hecuba, king and queen of the fabled Grecian city of Troy in Asia Minor. Just before his birth, a Trojan seer decreed that he would bring ruin to Troy unless he was killed. Priam and Hecuba both could not bring themselves to kill a newborn, so Priam entrusted his herdsman Agelaus with the job. However, Agelaus also could not bring himself to do it, so he abandoned the child on Mount Ida to die of exposure. A bear found and suckled Paris for days until Agelaus returned, deciding to adopt Paris as he was not dead.
While still a child, Paris earned himself the surname Alexandros, meaning "Protector of Men" after rounding up a gang of cattle thieves. Around this point, he became the lover of the nymph Oenone. When he later left her, she swore that if he was ever mortally wounded she would save him, as she could heal all wounds.
In celebration of Peleus and Thetis marrying, the god Zeus hosted a banquet to which all the gods were invited. The only exception was Eris, goddess of discord, who was a troublemaker. In revenge, she presented the gods with a golden apple inscribed "For the most beautiful". The goddesses Hera, Athena and Aphrodite were presented as the three most beautiful, and Paris was chosen to judge them. Eventually, he was presented with a bribe from each goddess; Hera offered him Europe and Asia, Athena offered him battle prowess and Aphrodite offered him the love of the most beautiful woman alive, this being Helen of Sparta. Paris accepted the final offer, not knowing that Helen was married to King Menelaus.
Due to her marriage, which Paris soon learned of, he had to sneak into her house to get her. According to some versions of the story, she fell in love with him due to the influence of Aphrodite, while others state that he simply kidnapped her (according to some of these latter sources, he also raped her). This led to Menelaus declaring war on Troy and invoking an oath that Helen's various suitors had made that they would defend her marriage to whatever man she chose. This led to most of the kingdoms of Greek mythology invading Troy.
Paris is portrayed as a coward in the original tale. During a duel with Menelaus that could have decided the war, Paris fled. Later, Paris was challenged to a duel by the Greek hero Diomedes, but simply shot him in the foot with an arrow rather than face him.
After the Greek hero Achilles slew Hector, the Trojan's greatest hero and brother of Paris, Paris avenged him by shooting at Achilles with his bow and arrow. With the help of the god Apollo, he wounded Achilles in the heel, his one weak spot. Achilles later died of his injuries.
Eventually, the Greek hero Philoctetes mortally wounded Paris in battle. A messenger was sent to Oenone begging her to help him, but she was bitter that he left her and refused. Paris subsequently died. Oenone became remorseful and killed herself.
After his death, the prophecy about Paris later came true when Troy was sacked by the Greeks. Priam, Hecuba and most of the other royals were killed, the exception being his sister Cassandra, who was dragged from the temple by Ajax the Lesser and enslaved (although she eventually died at the hands of Clytemnestra). This means that Paris, and by extension Aphrodite, was responsible for the deaths of the entire royal family.
Abandoned Oenone, his first wife, to seduce Helen. This made Oenone so upset and bitter that she refused to help him when he was killed in battle.
Abducted, and in some versions raped, Helen and took her back to Troy. This caused the Trojan War and the deaths of hundreds of people, eventually causing the fall of Troy.