R.I.P. Dumpster
In use from 1936 · US registration survived until 2008
The story
George Roby Dempster and his brothers, of Knoxville, Tennessee, put the 'Dempster-Dumpster' hoist-and-container system on the market in 1936. The registrations came later and lasted longer than the legend suggests: DEMPSTER DUMPSTER registered in 1953, and plain DUMPSTER in 1965 (no. 785,783), claiming first use back to 1 September 1936. Journalists lowercased it, the public adopted it, but no court ever declared it generic. The registrations were simply not renewed: the DUMPSTER one was cancelled in January 2008 for want of a routine maintenance filing, while the lowercase word carried on perfectly well without it.
The moral
Fame is a skip you can't climb out of. Paperwork, though, you can simply forget to file.
One grave, one country. Genericide is decided jurisdiction by jurisdiction and class by class: the same word can be the generic name of a product in one country and a live registered mark for the same goods in another. What is described here is the United States, and strictly speaking this one died of neglect rather than of fame.