Final answer:
The proletariat were the class of workers that Marxist revolutionaries believed would overthrow the czar and rule Russia.
Step-by-step explanation:
The class of workers that Marxist revolutionaries believed would overthrow the czar and rule Russia were known as the proletariat. According to Marxist theory, the proletariat, or working class, would recognize their exploitation under capitalism and rise up in revolution to establish a socialist society. Vladimir Lenin, a prominent Russian Marxist, believed that a vanguard party, such as the Bolsheviks, would lead and organize the proletariat in their revolutionary struggle.