Appearing In: Ant-Man and the Wasp
First introduced back in 1987, Ghost has mainly been a villain of Iron Man over the years, a vigilante and occasional gun-for-hire who is eager to sabotage and destroy corporations. Armed with a suit that allows him to turn invisible, he's a master hacker, a weapons expert, and an all-around genius, all adding up to make him one incredibly dangerous foe.
When Ant-Man and the Wasp arrives in July, it will be bringing with it a female version of the character portrayed by Hannah John-Kamen, who has been starring on the series Killjoys since 2015 and even has roles in this year's Tomb Raider and Ready Player One adaptations. Since Black Panther and Infinity War have understandably kept the focus off the Ant-Man sequel for now, little is known about its plot yet, let alone how Ghost figures into it, but her introduction is exciting nonetheless.
Purely on a technological level, the threat she poses to Scott and Hope is a unique one, and it'll be interesting to see a fight play out between someone who can turn herself and other objects invisible and a duo who can change the size of themselves and the objects around them. Though the wait continues to see how big her role will ultimately be, her inherent uniqueness alone has made her a new face worth welcoming to the MCU.