As Benjamin Franklin once said, “Tell me and I forget. Teach me and I will remember. Involve me and I will learn.” There are few leaders in the field of Veterinary Emergency and Critical Care that have both taught and involved so many fortunate veterinarians, nurses, students, and other members of the community. It is with great sadness that we now write this in memoriam to our respected colleague and dear friend, Lesley Geraldine King, MRCVS, MVB, Diplomate of the American College of Veterinary Internal Medicine, Diplomate of the American College of Veterinary Emergency and Critical Care, and a founding Diplomate of the European College of Veterinary Medicine-Companion Animal. Lesley passed away peacefully after a long illness on May 14, 2016. Lesley was a 1986 graduate of Dublin's veterinary school, but spent her entire career at the University of Pennsylvania. She first arrived at Penn to do a residency in internal medicine, but fell in love with emergency and critical care medicine and became an ACVECC diplomate in 1992. She was the Director of the Intensive Care Unit at VHUP for the last 23 years, developing it into the outstanding ICU that it is today. Her unique integration of internal medicine and intensive care medicine was the origin of critical care as we know it today. She was Professor of Intensive Care at the University of Pennsylvania, and a founder and pillar of Critical Care at Penn Vet and beyond. Lesley contributed to the training of over 50 residents that have gone on to become diplomates of ACVECC, as well as a multitude of interns, nurses, and veterinary students. She was instrumental in the development of the Intensive Care specialty, particularly in expanding and refining veterinary mechanical ventilation. Lesley was passionate about ACVECC; she spoke at IVECCS regularly, served on numerous ACVECC committees, and was president of the college from 1999 to 2001. Lesley's contributions were broad and widely recognized; she won every level of teaching award at the University of Pennsylvania including the 2012 Lindback Award in the Health Sciences. She also received the highest awards in the specialty of critical care, the Jack Mara Award for Scientific Achievement from the ACVECC and the Ira M. Zaslow Distinguished Service Award from the VECCS, both in 2013. Lesley was a sought-after international speaker and left lasting contributions to knowledge about treating and diagnosing challenging and life-threatening conditions of cats and dogs. Along with almost 50 scientific research publications, Lesley edited the authoritative Textbook of Respiratory Disease in Dogs and Cats, which has been translated into Japanese and Spanish; and the British Small Animal Veterinary Association Manual of Canine and Feline Emergency and Critical Care, now in its 2nd edition. When Lesley was not at work or speaking at a conference, she was enjoying her animals at home, which included dogs, cats, chickens, and her horses. She was an accomplished rider and spent many hours preparing for and competing in riding events. Her most recent passion was dressage, and she and her horse Romey competed at the prestigious Devon Horse Show just last year. Lesley was distinguished, accomplished, and passionate. She was loyal, pure in her focus, and single-minded in her devotion to her friends, her patients, her students, and her ICU. We mourn her loss but celebrate her life, her friendship, and her lasting accomplishments and contributions. In lieu of flowers, contributions can be made in Dr. King's memory for a student scholarship fund at the University of Pennsylvania School of Veterinary Medicine. Please make checks payable to the “Trustees of the University of Pennsylvania” and mail to the Penn Vet Development Office at 3800 Spruce Street, Suite 172E, Philadelphia, PA 19104.