While most people consider Hitler to have been the most-evil man who has ever lived, so far, he was NOT the antichrist. He failed to meet many of the Scriptural criteria for the AC.
He didn't gain power by overthrowing three other rulers. He was appointed as Chancellor by Hindenburg, the President of Germany.
He did not declare himself to be God, nor issue any "mark of the beast".
He never entered Jerusalem in his life, so he could NOT have performed the "abomination of desolation".
He was NOT cast alive into the lake of fire. He shot himself.
The TRUE beast/antichrist MUST fulfill ALL Scriptural criteria about himself PRECISELY, TO THE LETTER. That man is yet to come.