Filmation’s Masters of the Universe ran for 130 episodes across two seasons in 1983 and 1985, with no further new episodes. The toy line continued through 1988. The cartoon ended first.
But the Filmation episodes are still the canonical version of MOTU for the entire generation that watched them broadcast first-run. The animation reused frames aggressively to control costs. The voice cast was small enough that Alan Oppenheimer voiced four major characters (Man-At-Arms, Skeletor, Mer-Man, Cringer), Lou Scheimer voiced several more, and Linda Gary voiced nearly every female character on the show. The end-of-episode moral was a Standards-and-Practices requirement that the writers had to work around.
But the writers found a way. Larry DiTillio, Paul Dini, J. Michael Straczynski, Tom Ruegger, Bob Forward, and Robby London wrote scripts that within those budget and Standards constraints produced episodes like Prince Adam No More, The Problem with Power, House of Shokoti, Visitors from Earth, and the Granamyr cycle - episodes that operate as actual television rather than as toy commercials.
The Filmation MOTU is not the most polished cartoon of its era, and it is sometimes not even the most interesting MOTU cartoon (the 2002 MYP series is arguably more ambitious as a serial). But it is the one that established the canon. Every later cartoon, every reboot, every Mark Hamill / Sarah Michelle Gellar / Lena Headey re-performance is in dialogue with the Filmation run.