The mischievous Olympian in question is the Greek god Hermes, who is known for his trickery and mischief. He is often depicted as a messenger of the gods, and is the son of Zeus and Maia. The crossword solution for this term is 'ATE, ' which refers to Hermes' role as the god of thieves and commerce. He was known to have stolen cattle from Apollo, and was also responsible for protecting travelers and merchants.