Maya Hansen

Background and Iron Man 3
Dr. Maya Hansen is a brilliant botanist whose work helped create the game-changing biological process called Extremis. Her discovery has the power to change the human body, but it could be very dangerous if misused.

Maya met Tony Stark in a New Year's Eve party in Bern. In the same place they met Aldrich Killian who sought that Tony be associated with him, despite the contempt of Tony, Dr. Hansen accepts Killian's contact details with little interest.

After spending the night with Tony and see he had abandoned her, Maya decides to partner with Killian. Years later, Maya was present when the alleged Ten Rings attacked Tony Star's mansion.

She threatened to kill herself if Killian didn't let Tony go but Killian simply raised his gun a few seconds later and shot her through the chest, killing her.

Trivia

 * Maya was going to be the film's main antagonist, but it was changed to Killian at the last minute. This would have made her the first MCU villain to be female. However, that title eventually went to Hela Odinsdottir.