The antonyms for the phrase "were head of" can be numerous as it depends on the context in which it is used. If it refers to a position of leadership or authority, the antonyms can be follower, subordinate, or underling. If it refers to being ahead or at the forefront of something, then the antonyms can be trailing, lagging, or falling behind. Similarly, if it alludes to being the primary decision-maker or influencer, then the antonyms can be collaborator, team player, or equal participant. In general, the antonyms for "were head of" are varying and depend on the opposite meaning required in the particular sentence or situation.