Collingwood Hammer, often called "Hammerhead" by his students, is the Headmaster of Gotham Academy. Very little is known about his time before he became Headmaster of Gotham academy. As a boy he had attended The Carnival Midnight where his best friend Bernard disappeared, not to be seen again for "nearly a hundred years". He has been headmaster of Gotham Academy since at least 1985.
- Hammerhead's Roadster: Headmaster Hammer had a grey roadster that had a passing resemblance to a classic Porsche with a low split and raked windshield, sleek side intakes that hearken to a much more modern Porsche and personalized plates. The car was stolen by Colton Rivera, who intended to return it no worse for wear, when he and the Detective Club went to rescue Kyle Mizoguchi from Dr. Hugo Strange but it fell into a sinkhole after they parked.
- 22 Appearances of Collingwood Hammer (Prime Earth)
- 2 Images featuring Collingwood Hammer (Prime Earth)
- 2 Quotations by or about Collingwood Hammer (Prime Earth)
- Character Gallery: Collingwood Hammer (Prime Earth)