Xehanort used to be an insult given by the Master of Masters to one of the Masters as an anagram of No Heart. That was retconned though, now No Heart is the name of the armored shell of Xehanort left behind when Xehanort puts himself inside of Terra and becomes Terranort. You fight No Heart as the final hidden boss of Birth of By Sleep.
Another Nomura classic is Riku. Riku gets cloned along the series. Then Jiminy Cricket's journal decides it want to look exactly like Riku for some reason so when it creates a digital avatar of itself it shows up as Riku. Then time travel is introduced. So there's a whodunnit subplot in KH3 of whether the Riku who joins the Organization is Past Riku, Riku's Clone, or Jiminy Cricket's Journal. BECAUSE THEY ALL LOOK THE FUCKING SAME.
If you want to kill Nomura, I'm free on Thursday. Remember, Kingdom Hearts can still get gayer.