"The Greedy Giants" was the first episode of The New Casper Cartoon Show in 1963. Legendary Shamus Culhane handled the animation for this one, directed by Seymour Knietel. In it, Casper (Norma MacMillan) helps a weeping willow grow by locating a special potion. To gain the potion, Casper has to solve a riddle. If the ogre's voice sounds familiar, it belongs to Bradley Bolke, who used a similar voice for Chumley on Tennessee Tuxedo.
This set the tone for the series, as Casper was more heroic than in his theatrical shorts, which were mixed in with 26 made-for-TV shorts. That alone would explain how the series lasted as long as it did. The "Giants" in the title were the older trees, and they were really little more than doubting Thomases who didn't believe Casper would solve the ogre's riddle. This also was a rare case of Casper remolding his body to disguise himself.