Tirek as Serpentor, the Cobra Emperor from G.I. Joe.
Both are power-hungry and often selfish and brat-like at times. They are also somewhat similar in another way: in order to reach his full power, Tirek has to absorb the magic of other creatures. Serpentor only has his power - in fact, his entire existence - due to the absorption and re-composition of the DNA of history’s greatest military leaders and conquerors.
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