the enigmant man is Xenmas, the nobody of ansem who's real name is Xehanort" yes from the knight video" but Xehanort is the gut from KH1 and he is really just a creation made by diz on accident. Diz's real name is Ansem but when Xehanort was made he found the ansem reports and tok up the name ansem so The REAL ansem"aka Diz" took the name Diz to escape. when Xehanort continued ansem's studies he gained a nobody named Xemnas who found the Organization.
Xeenmas is his name because he thinks he is the nobody of ansem but really is Xehanort
Xehanort is No Heart jumbled up with an X
No Heart= Controller of Heartless