Gul Dukat

Gul Dukat is a major antagonist in Star Trek Deep Space Nine and is a high-ranking member of the Cardassian race (Gul is actually a title rather than part of his true name).

However like many antagonistic forces in Star Trek Dukat is not fully evil and will aid the protagonists on occassions, making him somewhat of a wildcard who can be an enemy one minute and an ally the next.