Fantasy football is a genre of board game or wargame which normally involves two teams of fantasy races (such as elves, dwarves or orcs) competing in an extremely violent variant of gridiron football. Violent future sports such as Rollerball may also be classified as fantasy football. However, this is less likely. Often the only resemblance to gridiron football for many fantasy football games is to get the ball into an end zone or goal, but these games still fall under the fantasy football genre.
The most famous of fantasy football games is Games Workshop's Blood Bowl series.
References
Fantasy football (fantasy world gaming) Wikipedia(Text) CC BY-SA