Rehashing all of his crimes would require a much longer article, not least because evaluating the claims of contemporary primary sources is a somewhat tricky historiographical enterprise. Philadelphia Magazine's Michael Coard has a good survey here; Howard Zinn's work on this is controversial but you can find a good excerpt at Jacobin, and an illustrated version at the Oatmeal.
Here are just a handful of specific cases, mostly culled from Laurence Bergreen's recent biography, Columbus: The Four Voyages, of almost unimaginable cruelty inflicted by Columbus and his crew during their time in the Caribbean.
D Matthews At VOX.COM
9 reasons Christopher Columbus was a murderer, tyrant, and scoundrel
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