Note: This article contains spoilers for Marvel’s Ironheart series.
Marvel Studios has finally introduced Mephisto to the MCU with Marvel’s Ironheart series, now streaming on Disney+.
In Episode 6, “The Past Is the Past,” Sacha Baron Cohen appears in the human form of Mephisto. It is revealed that Mephisto gave Parker Robbins (Anthony Ramos) the Hood, making a deal with him. You can see Baron Cohen’s Mephisto below.

In the finale, Riri Williams (Dominique Thorne), using her magic-infused suit, defeats Parker by removing his Hood. Later, at a restaurant, she meets Mephisto. During their conversation, Mephisto offers Riri anything she desires — but in return, she must work with him.
When he picks up a spoon, its reflection reveals Mephisto’s true, comic book-accurate face. He makes an offer and asks Riri to sign with him to help fulfill his millennia-old plan.

Riri has accepted his offer, and at the end of the show, she goes back to the past and finds out her best friend, Natalie Washington, is alive. Also, while they are hugging, Riri becomes the Herald of Mephisto.
Here’s the plot details for Ironheart:
Set after the events of Black Panther: Wakanda Forever, Marvel Television’s Ironheart pits technology against magic when Riri Williams (Thorne)—a young, genius inventor determined to make her mark on the world—returns to her hometown of Chicago. Her unique take on building iron suits is brilliant, but in pursuit of her ambitions, she finds herself wrapped up with the mysterious yet charming Parker Robbins aka ‘The Hood’ (Ramos).
The show, created by Chinaka Hodge for Disney+. In the show, Thorne stars as Riri Williams / Ironheart, Ramos as Parker Robbins / The Hood, Lyric Ross as Natalie Washington, Alden Ehrenreich as Joe McGillicuddy, Regan Aliyah, Manny Montana as Cousin John, Matthew Elam as Xavier Washington, Anji White as Ronnie Williams, Jim Rash reprises his role as the Dean of MIT, Shea Couleé stars as Slug, and Harper Anthony, Zoe Terakes, Shakira Barrera, Rashida “Sheedz” Olayiwola, Sonia Denis, Paul Calderón, Cree Summer, and Sacha Baron Cohen have been cast in undisclosed roles.
All six episodes of the Ironheart series are now available on Disney+.