Riri Williams/Ironheart (Marvel)

Ironheart, (Better known as Riri Williams) is the main protagonist of her new Ironheart and Invincible Ironman series. She later took on the mantle of Ironman in a very strange fashion.

Why She Sucks

 * 1) She is a blatant Mary Sue with no personality.
 * 2) Her backstory is rather poorly written, apparently, Marvel attempted to give Riri a tragic backstory to give her more "depth" and more "character development". However, as Literature Devil points out, Riri's backstory is very disjointed and she receives no character growth whatsoever.
 * 3) Like many of Marvel's more recent heroes, Riri's actions are sometimes more villainous instead of heroic. One time she literally stole materials from her school just to improve her Ironman suit.
 * 4) Riri Williams only exists just to replace Tony Stark, when yet there was nothing consistently wrong with the latter to begin with.
 * 5) Her suit's design took a step down from Stark's, barely looking like it was made to battle.
 * 6) She is otherwise a very pointless addition to Marvel Comics, and didn't have a real good reason to become the new Ironman.

Trivia

 * Riri Williams is apparently 15 years old in the comics.