I have 3 commons I brought inside for winter and clearly the orange one is the leader. It's far bigger than the other 2 and it won't let them eat when it's eating, it chases them around. Is it very likely that this leader fish is male or can the leaders of schools of fish be female?

Thanks.

I don't think dominance has anything to do with gender in goldfish (feel free to correct me if I'm wrong). You can often tell the gender by how fat the goldies are. Females will swell with eggs, usually more on one side than the other.
Mary