It was in an episode of the Little Mermaid show (the episode was titled "Heroes").
At one point in the show Ariel is being chased by a dragon. The dragon is big, black and spews green flames. Sound familiar? The dragon looked a lot like Maleficent as a dragon XD
sadly I don't know where to find a screenshot, but here's Maleficent
![User Image - Blocked by "Display Image" Settings. Click to show. User Image - Blocked by "Display Image" Settings. Click to show.](https://graphics.gaiaonline.com/images/s.gif)
the horns on the dragon in the Little Mermaid were slightly different