Tankies are not on the right-left axis. Tankies are on the libertarian-authoritarian axis. I could agree that tankies are anyone who is higher than you on the political compass.

Tankies are alluded to in this famous quote:

"Every line of serious work that I have written since 1936 has been written, directly or indirectly against totalitarianism and for democratic socialism, as I understand it." —George Orwell