Formed during World War II, HYDRA is a criminal organization dedicated to achieving world domination through terrorists and subversive activities. They want to achieve a fascist new world order. Originally founded by Hitler and Baron Wolfgang Von Strucker and is heavily influenced by Nazism. To join, one must make a death-oath.
HYDRA is rumored to be an ancient order that has existed since ancient times.
The modern version of HYDRA was created in the closing days of World War II by Hitler and Baron Wolfgang Von Strucker. HYDRA is to a combination of Nazi ideals joined with various ideals of death cults of South East Asia, including The Hand. The first Supreme HYDRA secretly answers to Von Strucker.
After the war, Strucker becomes the Supreme HYDRA.
During the following decades HYDRA becomes a global organization finding it way into various organized crime families, and terrorist organizations.
HYDRA works to destabilize the world economy and destroy government creditability. S.H.I.E.L.D. fights them secretly.
Madam Hydra preys on unrest in U.S. to try to recruit new members. Captain America and She-Hulk stops a HYDRA plot to destroy the New York Stock Exchange.