I don't know that Columbus was genocidal. He was a slaver, rapist, murderer, gold digger and all-round motherfucker for sure, so much so that the Spanish monarchy sent an envoy to arrest him, bring him back to Spain to be tried, and threw him in jail I think for a couple years. Aside from gold and spices sent from him back to the Spanish monarchs after his first arrival, he also sent back slaves and the queen was, presumably, utterly disgusted. But as far as I know, his exploits did not amount to "genocidal". I'm less certain about this than my other points, though.
Closer to "genocidal" would be Hernan Cortes, who pretty much took down the Aztecs.
Closer to "genocidal" would be Hernan Cortes, who pretty much took down the Aztecs.