If a character in a novel kills one of her own parents, it's called parricide. Your dad will be impressed by your vocabulary skills if you say mid-argument, "I'm so mad at you I could commit parricide!"
You can use the word parricide for the crime of murdering a mother or father, but it also means "one who kills their own parent." Historically, people who kill parental figures (like kings, for example) have also been charged with parricide. Parricide features as an important plot point in many books, ranging from "Harry Potter and the Half-Blood Prince" to "The Brothers Karamazov." Parricide combines Latin roots parus, "relative" and cida, "killer."