Powers: Used a "synthesizor" device to make sound waves take physical form.
Bio: A famous Russian musician who went over the edge after being permanently deafened by one of Green Arrow's sonic arrows. Discovering a centuries-old book of forbidden spells, Allegro enhanced his advanced synthesiser so that the sound of its keyboard generated demons. As a super-villain, Allegro battled the Justice League of America for revenge, but was defeated by Zatanna and Black Canary (II).
Years later, Allegro fled back to Russia. However, his synthesiser weapon was stolen by Pasha Gorkij who became the supervillain called the Maestro (IV). Although the JLA opposed the Maestro, it was Allegro who finally stopped the villain by destroying his own synthesiser. He was shot in the heart by Gorkij's brother in retaliation.