The Guardian is a man who wields a huge sword and is the final test at Necropolis.
Skulduggery spots him and approaches him. The Guardian then talks about the Merryn Sigil and how it will only last for 23 minutes. Skulduggery then replies saying he will return later. Later Scapegrace and Thrasher return to fight him instead. The Guardian impales the Sword in Thrashers head, in a fit of anger Scapegrace launches himself at The Guardian and takes him down. With this action they pass the test. The Guardian then explains the test was to see if he is pure of heart, and then adds that he was beyond honoured to have the zombie king as his opponent.
He wears robes similar to the Necromancer ones and wields a huge sword.