The character you play throughout the game. A assassin with insomnia who is hooked on a drug known as chronos. He can predict the future and slow down time
The little girl
A little girl zero meets after one of the early levels of the game and trips over his foot. Throughout the game zero becomes a sort of father figure for her after her fathers implied death. A popular fan theory is that she isnt real and is a manifestation of zeros conciense but ill leave that up to you.
The Psychiatrist is seen most levels and supplys our protaganist with a drug known as Chronos. He is also the one who gives us the assassination contracts. He is emplied to be employed by the new mecca government