Extreme Ghostbusters was AWESOME. It had character and creature designs by Fil Barlow, (not to be confused with Wayne Barlowe) who as far as I’m concerned is pretty much the Da Vinci of cartoon monsters. It was Fil who pushed for the inclusion of female and disabled ghostbusters, though he originally wanted two women on the team, and one of them was going to be paraplegic.
The network pretty much insisted that one woman was enough women in an action cartoon, and the wheelchair using ghostbuster was retooled into a dude. Fil did his best to get his ideas through, but we all know how it is with TV executives.
The monster you’re remembering is the GRUNDEL!
This is actually the only villain ghost in the series who returned from an episode of The Real Ghostbusters (seen here), and drew criticism from parents for behaving like a predator, though that was the whole damn point. The episode might be the most effective “stranger danger” lesson in 80′s children’s television; the Grundel scared most kids positively shitless at the time.
The entire show is actually easy to find in youtube last I checked, though NOBODY has high quality copies of this series and it hasn’t seen any official release or rerelease almost since it last aired on television. No Netflix or Hulu run, nothing.