Consider the question. Alan Sidney Patrick Rickman (21 February 1946 -- 14 January 2016) was an English actor and director known for playing a variety of roles on stage and on screen. Rickman trained at the Royal Academy of Dramatic Art in London, and was a member of the Royal Shakespeare Company, performing in modern and classical theatre productions. His first big television part came in 1982, but his big break was as the Vicomte de Valmont in the stage production of Les Liaisons Dangereuses in 1985, for which he was nominated for a Tony Award. Rickman gained wider notice for his film performances as Hans Gruber in Die Hard and Severus Snape in the Harry Potter film series.

Answer this question based on the passage: who plays snape in the harry potter movies?
 What is the step-by-step reasoning process to arrive at the answer: Alan Sidney Patrick Rickman?

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
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The relevant information is: Rickman gained wider notice for his film performances as Hans Gruber in Die Hard and Severus Snape in the Harry Potter film series.