Celestia Ludenberg
Celestia Ludenberg, or what is later revealed to be her real name, Taeko Yasuhiro, os the Ultimate Gambler and she is collected and cunning in nature, which helps her a lot in her gambling and during the trials. She is really intelligent, adapts quickly and is usually polite when talking to everyone but when things do not go her way, she is short tempered and will be hostile towards anyone that ruins her plans. Her cunning attitude is clearly shown as she tricks Hifumi into helping her murder Ishimaru and she cuts all loose ends by killing Hifumi as well. What made her murder was what Monokuma offered as incentive, which was a lot of money. She is ambitious and the reason why she wanted the money was because she had a dream to buy a mansion full of butlers that would serve her to her beck and call. During the trial, even after evidence is shown to prove that she was guilty, she stubbornly disagrees and the final evidence was her e-handbook which shows the owner's real name. She was forced to admit that her real name was Taeko Yasuhiro and she was taken away for the execution.