A man of action and a man of science, Dr. Henry Pym invented an amazing growth serum and a cybernetic helmet, and with them he became -- the Astonishing Ant-Man! Pym soon teamed with Janet Van Dyne, the winsome Wasp, and the two tiny titans went on to battle an array of mini- and maxi-sized menaces from the Scarlet Beetle to the Black Knight! But adventures in the microscopic world weren't enough for one of the Marvel Age's first super heroes. Soon, Ant-Man became the biggest Avenger there ever was -- Giant-Man!

Collects Tales to Astonish #27, 35-59.