What does the angel or spirit of Amalek represent?

“Amalek came and battled Israel in Rephidim.” (Exodus 17:8)

“…G-d maintains a war against Amalek, from generation to generation.” (Exodus 17:15)

The first Chassidic discourse by the Previous Lubavitcher Rebbe (after the passing of his father the 5th Rebbe in 1920 in Rostov, during the Russian Communist Revolution) was on the verse “Amalek is the first among the nations, and in the end he shall be destroyed” [the prophecy of Bilaam in Numbers 24:20]. The Rebbe explained that Amelek is the spiritual source and root of the spiritual evil of the seven evil nations – the Canaanites, Hittites, Amorites, Perizzites, Girgshites, Jebusites and Rephaim [Genesis 15:20-21]. But Amalek itself, the toughest of all evil forces, is separate from those seven, because it contains no element of good that can be salvaged by means of the divine service of humans. The “rectification” of the evil of Amalek is its utter eradication and destruction.

However, G-d “has set a limit to darkness” [Job 28:3]. The time allotted for this evil to exist is set, and when it expires, the evil will be utterly destroyed and annihilated, leaving no trace, because it does not possess any intrinsic form of true existence; it is a non-entity, even though it is extremely tenacious. Only with the help of Torah and faith in G-d can a person recognize this force as it resides within himself as evil, and take the necessary steps to dispel it from his mind and heart. This is difficult, because it includes the force of conceit that causes him to believe that his own intellectual innovations are correct, and/or that the way of Torah is wrong, G-d forbid.

Amalek is the supreme force of evil, above all the other evil forces. One of the first and most important tasks that the Messiah will accomplish once he is revealed to the world (speedily and in our days!) will be to destroy the spiritual force of Amalek. This will automatically remove the strength from all the other evil forces, so that the Messianic Era can begin.