BusyBox lawsuits
A run of US GPL suits from 2007 to 2010 that turned a tiny embedded toolbox into free software's most-used legal instrument.
BusyBox crams hundreds of Unix commands into one small binary, which is why it ends up in nearly every Linux router, NAS box and smart TV. That made it the ideal test case: vendors copied it, shipped it in firmware and forgot about the source. In 2007 the Software Freedom Law Center sued on behalf of its authors Erik Andersen and Rob Landley, starting with Monsoon Multimedia and moving on to, among others, Verizon, which settled in 2008.
In 2009 the campaign widened to around a dozen companies at once, including Best Buy, Samsung and JVC. Westinghouse never showed up, lost by default in 2010, and the court ordered its stock of offending TVs handed over to charity on top of damages. Landley later regretted the whole thing and wrote Toybox under a licence nobody can sue over.