Quacula was a backup feature in Filmation's New Adventures of Mighty Mouse & Heckle & Jeckle, which ran for 1 season on CBS in 1979. Actually, by the time the season ended, the series had been reduced to a half-hour. Why? Well, there's an explanation for that.
Animator and comics artist Scott Shaw! had created a vampire duck called Duckula three years earlier for a independent publisher, Star*Reach. When he saw that Quacula had a few too many similarities to his creation, Shaw! filed suit against Filmation. The matter was settled out of court, resulting in Quacula getting cancelled after all 16 episodes had aired. Those shorts had to be edited off subsequent rebroadcasts.
Frank Welker performs all the voices, except for Theodore Bear (co-executive producer Norm Prescott), forever scheming to evict Quacula and his egg-shaped coffin from the aging mansion they call home.
Up until now, English language versions of the shorts were hard to come by. One enterprising soul on YouTube put all 16 together (I believe), so binge to your heart's content, as the shorts add up to nearly 2 hours of comedy.
There are, of course, some flaws. For example, vampires don't cast reflections in mirrors or windows, and yet Quacula has a hand-held mirror he can use.
The British, of course, introduced us to Count Duckula a few years later, which was far more popular. I wonder if Shaw! had any issues with him.....