Doc Brown is his first one

Dr. Bunsen Honeydew

Doctor Sleep

Dr. Benjamin Franklin “Hawkeye” Pierce

Dr. Abraham Van Helsing

Dr. Wellington Yueh

Dr. Caligari

Dr. Egon Spengler

Dr. Raymond Stantz

Dr. Peter Venkman

Dr. Charles Xavier

Dr. Fraiser Crane

Dr. Heathcliff “Cliff” Huxtable

Dr. Mindbender