This is not as simple a question as it seems. So, Trundle was attached to Amma and tried to return the mother to the trolls, it cannot be said that this is an unambiguously negative motivation. Alberg, although narcissistic, sincerely believed that he was saving the city from the trolls, and in the end Alberg corrected himself. Kelly only appears in the first season and doesn't have time to do anything terrible; the same applies to other marras. Victoria appears in two episodes. The committee of three witches don't look like clear-cut antagonists, they try to abide by the witch rules, and they only appear in two episodes. Trevor, the Yule Lads, aggressive trolls like the two-headed troll, and other antagonists who barely appear in the series are way too non-serious antagonists. Who can be considered the main antagonist in Hilda?