I ran my first Linux distribution, (from Manchester Computing Centre) on a 386 processor, 20 years ago this year. This was console based only, so no X-Windows.
This was also the first ever Linux distribution, and was called the MCC Interim Linux distribution.
$ date --date "20 years ago" Mon Jan 24 22:03:50 GMT 1994
Since then i’ve run/managed RHEL, CentOS, Fedora, Debian, Ubuntu, Slackware, Gentoo, SuSE, SPARC Linux, SunOS, Solaris, OpenSolaris, SCO Unix, HP-UX, OpenBSD, FreeBSD, NeXTSTEP, OS X and a number of other Unix/Linux flavours in almost every possible use case/scenario imaginable.