(EDIT: I wasn't paying close enough attention to the OP. To add myself to the list of ironic deaths, I'm a big proponent of the importance of literacy and research. Ironic for me would be to get killed by a toppling shelf of library books.)
In 1871, lawyer Clement Vallandigham -- defending a man charged with murder -- accidentally shot and killed himself while trying to demonstrate how a man might accidentally shoot and kill himself. He won the case posthumously.
Jimi Heselden, the owner of the Segway company, died in a Segway accident.
Jerome Moody died by drowning in a pool at a party in New Orleans in 1985. Not just any party, mind you. It was party for the rec centre, celebrating their drowning-free season; there were four lifeguards on duty.
Moliere died of a tubercular coughing fit that started while he was performing as the central character in his play, "The Imaginary Invalid." The character was meant to be a hypochondriac.
Myra Davis -- one of the body doubles for the actress Janet Leigh from Hitchcock's Psycho -- was murdered in a shower in 1988 by a man obsessed with the film. The producers hadn't actually used her in the scene he was trying to re-enact; that was a different body double.
Garry Hoy died while trying to prove to his colleagues at TD Bank that the windows in their office building were unbreakable. He was proved right; when he threw himself against one of the windows, it didn't shatter. Instead it popped whole out of the frame and sent him plunging twenty-four storeys to his death.
The legendarily wealthy Marcus Licinius Crassus mounted a disastrous Roman expedition against the Parthian Empire in 53 BC. The Parthians cut his army to pieces and, when they finally caught him, executed him by pouring molten gold down his throat.
Felix Lloyd Powell penned what's known as the most optimistic song ever written, ?Pack Up Your Troubles in Your Old Kit Bag and Smile, Smile, Smile.? Many of his fellow soldiers in WWI credited it with getting them through the horrors of war. It didn't work for Powell himself; he died by suicide.
Timothy Treadwell, a somewhat loony self-anointed defender of the Grizzly bear, liked to camp for months at a time in the wilderness and soak up the gratitude of his ursine flock. He and his girlfriend were killed and eaten by a Grizzly in 2003.
