Ocram might really be Cthulhu. It would be epic if they made Cthulhu a boss. Unfortunately, Ocram is THE end boss for console and mobile. It would be really cool if he was on PC. You can fight Ocram for the price of 1 Mechanical Skull, 2 Mechanical Eyes, 10 Adamantite Bars, 5 Souls of Night and 5 Souls of Light.
Lepus might really be the easter bunny, despite they are dropped from Diseaster Bunnies. It might also be a huge pink Corrupt Bunny, despite it's dropped from that as well. Unfortunately, Lepus is only available in the mobile version. The Suspicious Looking Egg cannot be crafted, however, once you defeat Lepus, you can summon it infinitely.
The Old Man and Clothier might really be Skeletron. Since fighting it is really cheap, the Clothier Voodoo Doll can easily be farmed if you defeat 400 Angry Bones or more. If you do want to fight a boss on your first night, go to the dungeon and curse the old man. If you are scared, just do it.
The Ice Queen IS really Elsa. It's a Hardmode boss from the Frost Moon. It's the strongest boss and comes in the final waves. It's the only flying boss of the event, and is stronger than Everscream and Santa-NK1. You summon the Frost Moon with the Naughty Present. It can only be summoned at night, or it won't be consumed and it won't work.Finally, the Moon Lord is Cthulhu's (Ocram) brother. It is the final boss of Terraria, and you summon it by defeating the Lunatic Cultist and the four Celestial Towers, Vortex, Solar, Stardust and Nebula. It can also be summoned with a Celestial Sigil, for the price of 20 Solar Fragments, 20 Stardust Fragments, 20 Nebula Fragments, and 20 Vortex Fragments. To summon it that way, you must not have the Lunar Event on, or it won't work. It's only available on PC.