Remember me?

"Y" was first formed by "Z", and "X" was the 55th member to join it,

It was then called the worker's party, the final count included 859,009 members at 1933 from which its membership online declined.

"X" later went on to usurp the power of "Y" and became the most feared faces of the 30's.

"Y" was then criticized for its radical approach,

Though it was briefly successful, its success couldn't stand long, and was soon to be disbanded in 1945.

Identify "X" and "Y" which i am sure u already would have guessed so no points for that...

I want "Z".