Chair of the neurosurgery department and director of the Maxine Dunitz Neurosurgical Institute at Cedars-Sinai Medical Center in Los Angeles, California, he also is known for campaigning for funding of cancer treatment. A prolific surgeon—he’s performed more than 5,000 brain surgeries in his career—he’s frequently been featured as a hero in medicine with a reputation as a surgeon who will operate on tumors other doctors won’t touch. He has most recently turned his attention to finding a way to diagnose Alzheimer’s earlier.