Hush (reached by defeating Mom's Heart/It Lives in less than 30 minutes) Mega Satan (reaching The Chest or the Dark Room with the Golden Key or similar)

They are all in the last row of the note. With the release of Binding of Isaac: Afterbirth, there are 3 new additions to the post-it note. (A black outline for mark #8 indicates beating Greed Mode, while a red outline indicates beating Greedier Mode.) Marks with a red outline, as in the image below, indicate that the event was completed on hard mode. Each character has its own post-it note to fill out, and each addition to the note unlocks an item or cooperative baby for the game.

These symbols indicate certain events that you have completed with that character.