Alexarchus or Alexarch (Greek: ) was an Ancient Macedonian scholar and officer, son of Antipater and brother of Cassander. He lived around 350 to 290 BC. He is mentioned as the founder of a utopian town called Ouranopolis, in Chalcidice. Here he is said to have introduced a number of neologisms, which, though very expressive, appear to have been regarded as slang or pedantic.