Jacob Alexander Haller Jr. was an American pediatric surgeon who served as the first Robert Garrett Professor of Pediatric Surgery at the Johns Hopkins School of Medicine.
Haller Jr. was born in Pulaski, Virginia, to a family of dentists and physicians originally from York, Pennsylvania. His father, J. Alex Haller Sr., raised him with the help of two aunts, after his mother, Julia Allison, died. Haller Jr. contracted scarlet fever as a child, which led him to study medicine. He played basketball and football at Pulaski High School, graduating in 1944. Haller considered attending the University of Virginia in his home state, but was accepted at Vanderbilt University, where he had applied at his high school principal's suggestion. There, Haller met his future wife, Emily Simms, and played for the Vanderbilt Commodores men's basketball team until his senior year of college. Haller planned to enroll at the Vanderbilt University School of Medicine, but applied to the Johns Hopkins School of Medicine, having heard from professors that Hopkins specialized in surgery, his field of choice.