Sacha Baron Cohen’s Mephisto finally enters the MCU in 'Ironheart' twist that changes everything

Quick highlights:

• Mephisto, played by Sacha Baron Cohen, debuts in the final episode of Marvel’s Ironheart.

• The villain tempts Riri Williams with the resurrection of her deceased friend Natalie.

• Mephisto was long rumoured to appear in WandaVision, but Marvel kept his reveal for a surprise.

• Fans are speculating Mephisto could become a major supernatural threat across upcoming MCU phases.

After years of online fan theories and false alarms, Marvel Studios has officially introduced Mephisto into the Marvel Cinematic Universe, and not in the way anyone expected. The demon-like villain makes his first on-screen appearance in the season finale of Ironheart, shifting the tone of the tech-focused series into something much darker and supernatural.

Sacha Baron Cohen debuts as Mephisto in Ironheart finaleGetty Images

A surprise debut for a long-awaited Marvel villain

Mephisto’s arrival in Ironheart comes after years of speculation dating back to WandaVision in 2021. Many fans believed the shape-shifting demon was pulling the strings in Westview, but those theories led nowhere. Instead, Marvel has chosen Riri Williams’ show to mark Mephisto’s real entry into the MCU in a move that adds an unexpected mystical layer to the young inventor’s story.

Played by Sacha Baron Cohen, Mephisto appears as a slick, enigmatic figure who offers Riri a Faustian bargain. In exchange for helping her defeat Parker Robbins (The Hood), he promises to bring her late friend Natalie back to life. However, Natalie’s disturbing appearance at the episode’s end, veins blackened and soul clearly altered, suggests the cost of this deal will be far greater than Riri expects.

Sacha Baron Cohen’s performance leaves a strong impression

Cohen's portrayal is already drawing praise for its unpredictability. Alternating between British and American accents and casually referencing deals with figures like Ringo Starr and business moguls, his Mephisto is both humorous and menacing. The character’s playful menace and layered charm fit neatly into the MCU’s evolving tone, one that’s gradually embracing darker, supernatural arcs.

By making deals rather than declaring war, Mephisto reflects the comic book version of the character created in 1968 by Stan Lee and John Buscema. In the comics, Mephisto thrives on deception and trade-offs, often appearing when a hero is at their weakest emotionally.

What this means for the future of the MCU

While Ironheart may seem like an odd choice for Mephisto’s debut, it cleverly bridges Marvel’s tech-heavy legacy with its supernatural future. The deal between Riri and Mephisto could have ripple effects across multiple franchises. For instance, Mephisto’s comic book ties to Spider-Man: One More Day and Ghost Rider make him a logical fit for future MCU instalments like Avengers: Doomsday or the rumoured Midnight Sons project.

Some fans even speculate that Mephisto could become a central antagonist across Phase 6 and beyond, perhaps rivalling the impact of Thanos or Doctor Doom.

Riri’s fate remains uncertain

The finale leaves Riri marked by the consequences of her deal, quite literally, as black markings begin to spread on her skin. With no official announcement of a second season yet, her arc may continue in larger team-ups or crossover events.

But one thing is clear: Mephisto is no longer a running gag or fan theory. He’s real, he’s dangerous, and he’s only just begun.