Sometimes, but other times I have seen people refer to fictives as alters that are based on fictional characters... but still trauma related. E.g. sometimes people have animal alters (we have one) because in that trauma related event it was helpful for the child to imagine themselves as a wolf that could outrun the abusers. The animal alter isn't "made up", it's just a child's brain using what a child knows to cope with trauma.
I know another system that has a alter who believes itself to be a wall, because in the child's brain it was safer to be a part of the wall than the child being abused in the room.
So in that context and especially in this day and age where even very young children have access and ongoing exposure to multi media, I can easily imagine a child taking on the characteristics of a fictional character to escape the reality of abuse.
I don't know if there is an actual accepted term for alters that take on the characteristics of fictional characters as a response to trauma or not, but I have seen the term "fictives" used to describe bona fide trauma alters before.