Alexander I of Epirus (Ancient Greek:Ἀλέξανδρος Α'; c. 370 BC^[1] – 331 BC), also known asAlexanderMolossus (Ἀλέξανδρος ὁ Μολοσσός), was a king ofEpirus (343/2–331 BC) of theAeacid dynasty.^[2][3] As the son ofNeoptolemus I and brother ofOlympias, Alexander I was an uncle, and a brother-in-law, ofAlexander the Great. He was also an uncle toPyrrhus of Epirus.

Alexander I
King of Epirus
Coin of Alexander I. Obverse: head of Zeus. Reverse: thunderbolt, caption ΑΛΕΞΑΝΔΡΟY ΤΟΥ ΝΕΟΠΤΟΛΕΜΟΥ.
Reign	343/2 - 331 BC
Predecessor	Arybbas of Epirus
Successor	Aeacides of Epirus
Died	331 BC
Issue	Neoptolemus II of Epirus
House	Aeacidae
Father	Neoptolemus I of Epirus
Religion	Ancient Greek religion

Neoptolemus I ruled jointly with his brotherArybbas. When Neoptolemus died in c. 357 BC, his son Alexander was only a child and Arrybas became the sole king. In c. 350 BC, Alexander was brought to the court ofPhilip II of Macedon in order to protect him. In 343/2 in his late 20s, Philip made him king of Epirus, after dethroning his uncle Arybbas.^[2]

When Olympias was repudiated by her husband in 337 BC, she went to her brother, and endeavoured to induce him to make war on Philip. Alexander, however, declined the contest, and formed a second alliance with Philip by agreeing to marry the daughter of Philip (Alexander's niece)Cleopatra. During the wedding in 336 BC, Philip was assassinated byPausanias of Orestis.

In 334 BC, Alexander I, at the request of the Greek colony ofTaras (inMagna Graecia), crossed over intoItaly, to aid them in battle against severalItalic tribes, including theLucanians andBruttii. After a victory over theSamnites and Lucanians nearPaestum in 332 BC, he made a treaty with theRomans. He then tookHeraclea from the Lucanians,Terina from the Bruttii, andSipontum on the Adriatic coast. Through the treachery of some Lucanian exiles, he was compelled to engage under unfavourable circumstances in theBattle of Pandosia and was killed by a Lucanian. He left a son,Neoptolemus, and a daughter, Cadmea.^[4][5][6]

In a famous passage,^[7]Livy speculates on what would have been the outcome of a military showdown betweenAlexander the Great and theRoman Republic. He reports that as Alexander of Epirus lay mortally wounded on the battlefield at Pandosia he compared his fortunes to those of his famous nephew and said that the latter "waged war against women".

• Lendering, Jona. "Alexander of Molossis".Livius.org, 2004. Birth and kingship dates are incorrect)