Ithoi the Navigator is Captain Tock's second-in-command, and one of the crew members who have moored in Corsair Cove after supposedly being cursed.
During The Corsair Curse, the player uncovers that the curse that has befallen the crew was actually Ithoi poisoning the crew's dinner, due to Captain Tock's consideration of firing him and replacing his position as second-in-command with Francois, Arsen's brother, as they no longer need a navigator now that they have settled in the Corsair Cove. By "cursing" the crew with poisoned food, Ithoi hoped that he would be able to stay with the crew due to his knowledge of curses. He too pretended to fall under the "curse". The player eventually proves that Ithoi was responsible for poisoning the crew and faking the "curse", so Captain Tock has the player kill him for his treachery.
He is a capable mage, being able to use elemental bolt spells as well as the Curse spell.
He can be fought in the Nightmare Zone after the quest is complete. If fought in hard mode, he will attack faster and use elemental wave spells. Be wary of fighting him in Nightmare Zone, especially in hard mode, without Overload potions as he will drain Defence levels rapidly.
- Using any variation of abyssal whip on him while he is lying down will cause him to say Arrr, RuneScape isn't that sort of fantasy game, in case ye hadn't been told that a-fore today.
- This is a reference to Mod Ash adding additional dialogue when attempting to use one on an NPC who is tied up during the Carnillean Rising quest in RuneScape 3. The Corsair Curse and Carnillean Rising quests were both developed by Mod Ash.
- In Nightmare Zone, Ithoi is renamed as the "Corsair Traitor".
- When fought in hard mode, he did not have (hard) added after his name; this was added in an update on 11 January 2018.