Board Thread:Show-Related Questions and Answers/@comment-1031724-20160806042520/@comment-25926288-20160806104735

The main villian or rather the sole villain of the entire season is Rumple. He's just more background than the others at many points in the season.

So, it's like:

Overall: Rumple

Season 4A main: Ingrid; secondary: Rumple

Season 4B main: Rumple; secondary: Isaac, Queens of Darkness; tertiary: Zelena.