Headon (헤돈, Hehdon; "Headon") is the Guardian of the First Floor and the caretaker of the Tower.
Although most Guardians normally stay on their Floors, Headon seems to be the only Guardian with the ability to visit other Floors of the Tower. This is because he teleports into any of the 134 Floors of the Outer Tower or the Middle Area when selecting Regulars.
(Source: Tower of God Wiki)