In Greek mythology, Amphilochus was the younger son of Amphiaraus and Eriphyle and the brother of Alcmaeon.
Eriphyle persuaded Amphiaraus to take part in the Seven Against Thebes raid, though he knew he would die. She had been persuaded by Polynices, who offered her the necklace of Harmonia, daughter of Aphrodite and Ares. Amphiaraus reluctantly agreed to join the fatal battle and asked his sons, Alcmaeon and Amphilochus, to avenge his foreseen death. In the battle, Amphiaraus sought to flee from Periclymenus, the son of Poseidon, who wanted to kill him, but Zeus threw his thunder and the earth opened to swallow Amphiaraus together with his chariot. Alcmaeon killed his mother and exiled himself.
Argive Amphilochus was a prominent seer, and founded several oracles, most importantly at Mallus, a pre-Greek site in Cilicia, and, acting with his half-brother Mopsus, the oracle of Apollo at Colophon in Lydia. According to Herodotus, Amphilochus travelled farther east and founded a Posideion just beyond the mountain-pass "gate" in the Amanus between Cilicia and Syria.
Amphilochus is named among the suitors of Helen in some accounts. After the Trojan War, according to Thucydides (2.68), not caring for the situation in Argos, he founded "Amphilochian Argos and the whole region of Amphilochia" on the Ambracian Gulf, a non-Greek settlement later Hellenized by its Ambraciot neighbors. Also after the Trojan War, he may have been killed either by Apollo, or by his half-brother Mopsus, whom he reciprocally killed in single combat; however, these myths may concern his nephew, also named Amphilochus.