Eye of Cthulhu

"Have you seen Chith... Shith.. Chat... the big eye?"

- The Merchant about the Eye of Cthulhu.

"You feel an evil presence watching you..."

- The Eye of Cthulhu has been summoned.

The Eye of Cthulhu, also mistakingly called Chith, Shith, Chat and the Big Eye by the Merchant, is a minor and one of the most recognizable antagonists of Terraria, even more so that the final bosses of the game, the Wall of Flesh and the Moon Lord. It is second weakest boss in the game, in front of the King Slime. It is a giant, floating eye that claims to be the very eye of the Great Old One; Cthulhu.

Terraria
The Eye of Cthulhu has a 1/3 chance of appearing in the world if... The Eye of Cthulhu can also be summoned by using the "Suspicious Looking Eye".
 * The Eye of Cthulhu hasn’t been beaten yet.
 * The Player has 200 HP and more than 10 DEF.
 * Three Town NPCs are living with the Player.

Upon being called, the Player will get the status message stating that "You feel an evil presence watching you...". After 1 minute and 21 seconds after the status message, the Eye of Cthulhu will spawn and begin attacking the Player(s).

The Eye of Cthulhu has two phases, the first phase is in its First Form. The Eye of Cthulhu can phase through walls and will attempt to float over the Player while summoning Servants of Cthulhu, that upon death, will drop Hearts and Stars. Upon summoning 3-4 Servants of Cthulhu, the Eye itself will try to ram into the Player three times before summoning 3-4 more Servants of Cthulhu and will keep repeating this cycle.

After the Eye of Cthulhu's HP becomes lower than 50%, it will begin spinning, chipping away blood and flesh before revealing its True Form and will begin the second phase. The Eye of Cthulhu will not ram the Player 3 times but more aggressively, once it is done ramming, it will hang in the air but will no longer spawn Servants of Cthulhu. The Eye of Cthulhu in its First Form has 2,800 HP, 15 ATK and 12 DEF, in its True Form, the Eye of Cthulhu in its True Form sacrifices defense for attack, it has 1,400 HP, 23 ATK and 0 DEF.

In Expert Mode, the Eye of Cthulhu spawns more Servants of Cthulhu and it’s True Form now spawns 3-4 Servants of Cthulhu. The Eye of Cthulhu will use its normal strategy until 1/4 of its HP has been drained, it will then begin rapidly attempting to ram the Player, and does so the more of its HP is drained, being almost endless when close to death. The Eye of Cthulhu in its First Form has 3,640 HP, 30 ATK and 12 DEF, in its True Form, it has 2,364 HP, 36 ATK and 0 DEF, at 1/4 of its HP its ATK is upgraded to 40.

If the Player is unable to kill the Eye of Cthulhu before dawn or runs away from it, the Eye of Cthulhu will despawn, but instead of simply despawning like if the Player runs away, the Eye of Cthulhu will fly away if it becomes dawn.

Trivia

 * If the Player has all the requirements to summon the Eye of Cthulhu and talks to the Merchant, he will tell them that he senses something watching him, but is incapable of saying its name.
 * The Merchant not being able to say the Eye of Cthulhu's name is a reference to the fact that Cthulhu's name in unpronounceable in the Cthulhu Mythos.
 * The Eye of Cthulhu's First Form has a blue iris with green centered around its pupil, making it appear to have Central Heterochromia.
 * Despite being called the "Eye of Cthulhu", the Eye itself does not appear to be an octopus eye or glowing.