Daredevil Vol.1 #15
The Ox is convinced by his cellmate, Dr. Karl Stragg, that if the two can escape, the good doctor will make Ox smarter; Stragg double-crosses the Ox and switches bodies with the brute; DD tracks down the new and improved Ox only to defeat him permanently.
Printed: Apr 1966
Writers: Stan Lee
Art: John Romita and Frank Giacoia
Cover: John Romita