William Zellmer currently serves as writer-in-residence for the American Society of Health-System Pharmacists (ASHP). A former deputy executive vice president for ASHP, Mr. Zellmer has worked for the organization in a range of capacities since 1970.

Among his many career honors, Mr. Zellmer was awarded the 2009 Donald E. Francke Medal from ASHP. He has also served as the John W. Webb Visiting Professor in Hospital Pharmacy at Northeastern University in Boston, and as a visiting pharmacist at the Academic Medical Center at the University of Amsterdam in the Netherlands.

Mr. Zellmer earned his bachelor of science in pharmacy at the University of Wisconsin in 1967, and completed his hospital pharmacy residency at the United States Public Health Service Hospital in Baltimore, where he later finished his master's in public health (health policy and management) at Johns Hopkins University School of Public Health.