In the game "Terraria", which of these bosses are pre-hardmode bosses?

In the game Terraria, the Eye of Cthulhu is considered a prehardmode boss because it is one of the first bosses that players encounter before entering the harder mode of the game. As a prehardmode boss, it possesses a moderate level of difficulty and serves as an introductory boss to the game's progression. Defeating the Eye of Cthulhu allows players to obtain valuable resources and progress further in their exploration and gameplay.