All twenty-two episodes of Star Trek: The Animated Series is now available to stream online for free at tv.com. The 1970’s cartoon originally ran from 1973-1974 and featured the voices of original Star Trek actors, William Shatner, Leonard Nimoy, DeForest Kelley, James Doohan, Nichelle Nichols, George Takei, and Majel Barrett.
Source: TV.com