Cthulhu. Because the Windows OS isn’t bad enough!
In all fairness, Cthulhu was originally open source, until Microsoft made its own version as part of the Elder Gods Applications Suite, only to get into a nasty lawsuit from Oracle, which claimed that MS had used the “look and feel” of its copyrighted demonic alien gods, as well as violating its copyrights for the use of the circle, triangle and pentangle geometric forms.