Mark Jozef Albert, Baron Waer (born 10 March 1951) is a Belgian physician, biomedical scientist, and former Rector of the Katholieke Universiteit Leuven.
From 1983 to 1985, Waer was a postdoctoral research fellow at the Stanford University School of Medicine.
In 1992, he was promoted to professor at KU Leuven faculty of medicine, where he specialised in nephrology and immunology.
In 1994, he was pointed the Director of Laboratory for Experimental Transplantation at KU Leuven.
From 1998 to 2005, Waer was the Medical Director of KU Leuven's teaching hospitals.