Dr. Thomas Killeen joined Haddonfield Pediatric Association in 2013. He received his bachelor of science in premedicine from Pennsylvania State University and his medical degree from Drexel University College of Medicine in Philadelphia, Pennsylvania. During his pediatric residency at St. Christopher's Hospital for Children, Dr. Killeen volunteered his time at the Ronald McDonald House and the Eliza Shirley House-Shelter For Women where he addressed the medical needs of children residents.

Dr. Killeen is certified by the American Board of Pediatrics and is a fellow of the American Academy of Pediatrics. He is affiliated with Virtua Hospital in Voorhees, New Jersey. His clinical interests include concussion management.