The term that is typically used for this is karoshi (unsurprisingly, a Japanese term). To the best of what I have been able to determine, there have not been any cases where an academic at a university has been diagnosed as having died through Karoshi. There are some significant deaths, however, of people in industry who could certainly be considered as being part of the broader community of scientists, notably a lead engineer at Toyota and more than one engineer in Taiwan.
Note, however, that there is also a strong cultural component, both in the manner of death and the classification of that death. An American, for example, might be less likely to die quietly at their desk and more likely to commit suicide or engage in criminal activity (see, for example, the tragedies in the development of the Apple Newton). Moreover, since karoshi is not generally recognized in American culture, deaths that might be attributed to it in a Far East nation would likely be blamed on the proximate cause of death instead.
A Harvard Law student named William Thornton Parker, Jr. died of over-studying (according to Harvard).
There is a much newer reported case of someone dying from playing Starcraft for too long without eating or sleeping properly. Some of the comments point out Parker Jr. could have had a pre-existing condition that was exacerbated by fatigue. I present the StarCraft case shows that someone with no outward signs of a fatal illness can die from exhaustion.
Im not sure what limits death through working too hard, as im not sure what that would do to the body. However, there are some cases when working too late or 'hard', accidents happen. A student was killed working at night on a lathe. This type of late night work accident is used in my schools as the reason not to work while tired or alone at night.
Marie Curie might fall into this category, although her death was not from working too hard per se. To quote wikipedia:
Marie Skłodowska-Curie (7 November 1867 – 4 July 1934) ... conducted pioneering research on radioactivity. She was the first woman to win a Nobel Prize, the first person (and only woman) to win twice, the only person to win twice in multiple sciences, and was part of the Curie family legacy of five Nobel Prizes. She was also the first woman to become a professor at the University of Paris, and in 1995 became the first woman to be entombed on her own merits in the Panthéon in Paris.
Regarding her death:
Curie died in 1934 at the sanatorium of Sancellemoz (Haute-Savoie), France, due to aplastic anemia brought on by exposure to radiation – including carrying test tubes of radium in her pockets during research and her service during World War I in mobile X-ray units created by her.