John Barrett Heiser, widely known as JB, was a retired senior lecturer at Cornell University and a former director of the Shoals Marine Laboratory, which is jointly operated by Cornell University and the University of New Hampshire.

After graduating from Princeton High School in 1963, he attended Purdue University, where he majored in biology, graduating in 1967. That summer, he took his first formal course in marine science at the recently founded Shoals Marine Laboratory, located on Appledore Island off the Maine coast. In the fall, he entered a graduate program in the marine science field at Cornell.

JB soon started teaching at the Shoals Marine Laboratory as a graduate teaching assistant. In 1970, he was placed in charge of the lab sections of a new Vertebrate Biology course at Cornell on the Ithaca campus. That led to his co-authorship of Vertebrate Life, a widely used textbook that was first published in 1979.

In 1979, JB became the second Director of the Shoals Marine Lab, a position he would hold for fourteen years. After stepping down from that role, he traveled extensively, both independently and as faculty for Cornell Adult University, the Smithsonian Institution, and other groups offering field-based education, including the Organization for Tropical Studies in Costa Rica.