Mariota, Countess of Ross (Mairead, also called Mary and Margaret; died 1440) was the daughter of Euphemia I, Countess of Ross and her husband, the crusading war-hero Walter Leslie, Lord of Ross. Upon the death of her brother, Alexander Leslie, Earl of Ross, she became the heir-presumptive of her niece Euphemia II, Countess of Ross although her husband Domhnall of Islay, Lord of the Isles pressed Mariota's superior claim to the earldom.