GNU Hurd is an operating system based on the GNU Hurd kernel. It is intended to supplement the GNU userspace utilities. Currently there are only a limited number of distributions that include it as the kernel, as it is not ready for production. It is built on top of a microkernel, GNU Mach, with daemons running on top of it.
Distributions that include HurdEdit
There are versions of the Arch and Debian operating systems that use the Hurd kernel instead of the Linux kernel.