It's easy to assume that He-Man & the Masters of the Universe marked its 30th anniversary last year, but that would not be true. Mattel introduced the characters in 1982 with their initial toy line, and landed a licensing deal with DC Comics for a miniseries, and a then-once-in-a-lifetime meeting with no less than Superman. The cartoon we all know launched in September 1983, more than a year after the toy line debuted.
In 2002, Mattel marked the 20th anniversary of the Masters line with a relaunch, and tasked independent producer Mike Young (Butt Ugly Martians) to produce a new He-Man cartoon which, unlike its predecessor, didn't air in the daytime. Instead, Cartoon Network slotted He-Man in their Saturday primetime lineup for the course of its run, which only lasted two seasons, as opposed to three for the original.
Young adapted and/or reimagined classic episodes of the original series, but at the same time, he also added some backstory that Filmation couldn't do, such as the origin of Skeletor, He-Man's ancient nemesis.
Skeletor started off as a sorcerer named Keldor, and his bony appearance is the result of one of his potions backfiring against him in a final battle against then-Captain of the Guard Randor, as you'll see in the TV-movie, "The Beginning":
The animation's much better than the original, thanks to modern technology. Unfortunately, CN gave up on the show way too soon. Now, there are people hoping Mattel tries again. One can hope, but don't hold your breath.
Edit: 5/25/15: This is the 2nd review of the series.