In a MUCK, wizards are players with a special flag set on their database object.
They serve a similar purpose as they do in
MOOs (see that writeup under wizard). They can get around most permissions checking, and set their MUF or MPI code to do so. As in a MOO, a wizard can also force a server database save, shutdown, or restart.
On some MUCK servers (most notably GlowMUCK, NeonMUCK, and ProtoMUCK) there are multiple wizard levels, each with different levels of control. (Typically called Boy, Archwizard, Wizard, and Mage or W4, W3, ...)
On most MUCKs most wizards powers are limited, especially in the area of creation and control of other wizards and low-level manipulation of the database, and total power is reserved for the special #1 (a database number) wizard character, also known as God or on MUCKs with multiple wizard levels the Man.