Dreadnautilus5000🌳
Plantera
Just now, I reached 500 messages. However I didn't get the "This is....Terraria!" Trophy, which unlocks the Brain of Cthulhu title. I got the other trophies for reaching certain numbers of messages, but that was before the forum update (the one that added profile banners and profile post attachments). So I thought that it might have had something to do with the update.