CentOS (from the CentOS Project) is available for POWER8 with both Big Endian and Little Endian support ! Starting with version 7 (1511), it can be downloaded from CentOS.org website and installed on POWER8 servers.
With the entire version ported to IBM POWER, all the tools and packages you are used to are available right away. While keeping the same look-and-feel and commands, it leverages the IBM Power Systems platform to provide extreme performance, higher levels of availability and increased flexibility.
Where?
http://mirror.centos.org/altarch/7/isos/
It is available in both Big and Little Endian environments 😉