Jan Vincents Johannessen (born 25 May 1941) is a Norwegian physician, cancer researcher, hospital director, painter, text writer and composer.

He is known for his research on cancer, and has published books on diagnostics by the use of electron microscopy.

He has served as manager of the Norwegian Radium Hospital.

[1][2] He is a fellow of the Norwegian Academy of Technological Sciences.

This biographical article related to medicine in Norway is a stub.