I'm fairly certain a lot of very influential software came from the hands of Bill Gates as well such as the FAT filesystem which is still used, the original MSDOS and BASIC Interpreter which made a huge impact.

Of course, that's all mostly because much of that was bundled with the original MSDOS.

Also, in terms of video games, a great deal of innovative techniques and games game from John D. Carmac, which of course also is a result from Id Software pushing it.

FFMPEG & QEMU from Bellard, perhaps?

It's hard to imagine either Linux or Git if Ken Thompson and Dennis Ritchie hadn't laid the foundation.

Brian Kernighan