Leo Spiller is a fictional character on the F/X television series Dirt, played by Will McCormack.
Leo is Lucy Spiller's younger brother, to whom she is reasonably close. He appeared to cope with their father's suicide slightly better than she has, and is closer to their mother than she. He identifies himself as bisexual, although his sister argues that he is gay and in denial. He strongly disapproves of his sister's career.
After decorating fictional A-list action movie actor Jack Dawson's home, he realizes that Jack Dawson is secretly gay after he comes onto him. The two have a relationship outside public eyes, but a suspicious Lucy has Don Konkey follow him to discover the truth. After he catches Jack cheating on him with his male gym instructor, he pushes Lucy to out Jack on the cover of her magazine, DirtNow. He helps Don to get pictures of Jack, for which Jack beats him up.
Later, he feels guilt for the damage Jack's outing has done to his children at school and to his wife. Jack publicly denies being gay on national television, but backs out of a court case when Lucy expresses her confidence in winning such a court case. Leo regrets his actions in outing Jack, and seeing that Lucy does not care as strongly, he decides to sever all ties with her.
In episode 12, he returns to Lucy with new girlfriend Lumina in town, asking to stay at her apartment. While staying there, it is revealed in the season finale that he was the one who was stalking Lucy. He claims he did it in order to teach her a lesson about how she treats what he describes as "her victims". Lucy, crying, berates him both for his "endless quest for God", his "sexual indecision" and what she sees as the mislaid projection of the anger he has over his father's suicide. He echoes her father's suicide note when he justifies that he did it for her - the only alternative to his own suicide, which he explains he had almost succeeded in doing beforehand. Lucy does not press charges, but demands he stay away from her. After placing his belongings on her driveway, Lucy is attacked by Julia Mallory. After Mallory attempts to flee the scene, she is run over by Leo, who drives away following this.
At the end of the Second series he calls Lucy to inform her of their mother's death, and the two blackmail her plastic surgeon to make her look good for the open casket funeral.