In Japan? Maybe. Globally? Not even close. As recently as 2004, there was a tsunami in the Indian Ocean that caused over 200,000 casualties (compared to the 15,000-20,000 casualties of the 2011 Japanese tsunami).
Sorry if it seemed insensitive, I didn't mean the most harmful, but the most powerful in terms of physics, as an engineering reference point if you will.
Death toll really isn't a good number to use for gauging the risk to nuclear reactors. Indonesia was more vulnerable to tsunami damage and deaths than Japan for basically the same reasons why Japan has nuclear power plants and Indonesia doesn't.