Dr. Samuel Register

A DC Comics villain and foe of the Teen Titans, Zookeeper deliberately infected himself with the same virus that granted Beast Boy his shape-shifting abilities, having previously worked alongside Beast Boy's parents. This gave him a similar power to transform into animals.

Dr. Samuel Register is a DC Universe figure who stepped onto the page in 2004's Teen Titans #14, courtesy of the sharp creative pairing of Geoff Johns and Tom Grummett — a debut that planted him squarely in the rich, character-driven Modern Age of DC storytelling. His appearances span a remarkable two decades, threading through Teen Titans, Titans, and even the landmark Infinite Crisis Omnibus, which speaks to a staying power that outlasts many a more prominent name. Though his catalog footprint is modest, he keeps genuinely distinguished company — sharing pages with the likes of Green Lantern, Firestorm, and Beast Boy — and that kind of association marks him as a figure woven into the connective tissue of the DC universe rather than its fringes. For the dedicated collector tracing the deeper layers of the Titans' world, Dr. Samuel Register is exactly the sort of discovery that rewards a thorough long-box dive.