ksu - the Kerberized super-user command in Linux and other *nix-like operating systems.

From the man page :

ksu is a Kerberized version of the su program that has two missions:
one is to securely change the real and effective user ID to that of the
target user, and the other is to create a new security context.

One should not confuse ksu with KSU, the initials of Kansas State University, which is also known as K-State.
(For what it's worth, K-State is actually the preferred shortened version of the university's name, since the initials KSU are shared by several other institutions as well as at least one operating system command.)