Blackheart is a character appearing in American comic books published by Marvel Comics, usually as an adversary to the superhero Ghost Rider. Created by writer Ann Nocenti and artist John Romita Jr., Blackheart first appeared in Daredevil #270 (September 1989).

Blackheart is a demon and the creation of Mephisto, who he has opposed on several occasions. In the 2024 series Avengers Academy: Marvel's Voices, Blackheart refuses to retrieve Billy and Tommy Maximoff for Mephisto, which results in Mephisto transforming Blackheart into a human and banishing him to Earth. Significantly weakened, though retaining a portion of his powers, Blackheart seeks refuge at the Avengers Academy and becomes a student there.

The character has also appeared in other media, such as the 2000 video game Marvel vs. Capcom 2: New Age of Heroes and in the 2007 film Ghost Rider, in which he was portrayed by actor Wes Bentley.

The character was created by Ann Nocenti and John Romita Jr. and first appeared in Daredevil #270 (September 1989).

Blackheart was redesigned for the series Avengers Academy: Marvel's Voices, where Mephisto transformed him into a human. Writer Anthony Oliveira and artist Bailie Rosenlund decided to give Blackheart a gothic appearance, with red eyes and a hairstyle resembling his demon form's spiky head. Blackheart has thorn-like tattoos on his upper body, reminiscent of the bramble bushes of Christ's Crown.

Centuries of murder in a locale named Christ's Crown, New York, draws the attention of a Hell-lord, Mephisto, who creates a "son," Blackheart, from evil energy. Blackheart explores the nature of evil under his father's tutelage, clashing with and failing to corrupt Daredevil and Spider-Man. Mephisto draws Daredevil, Brandy Ash, the genetically engineered Number Nine and the Inhumans Gorgon, Karnak, and Ahura into Hell, where Blackheart tries to tempt them. However, he is impressed by humanity's free will and concludes that evil cannot hope to win out against good. When Mephisto learns of Blackheart's change of mind, he banishes him to Earth, warning him that if he ever uses his power again, he will be driven mad.

Blackheart returns to Christ's Crown and lures Ghost Rider, Punisher, and Wolverine to the town, hoping to recruit them in his war against Mephisto. When the three refuse, Blackheart brainwashes the entire town and kidnaps a young girl all three men had befriended. The group follows Blackheart and the girl into his realm and defeats him. Unexpectedly, the girl offers Blackheart forgiveness, which he does not know how to respond to. It is later revealed that Blackheart only needed the girl's blood. Brandishing a dagger tipped in her blood, Blackheart kills Mephisto and takes over a portion of Hell.

Blackheart creates a group of Spirits of Vengeance to oppose the Ghost Rider, Noble Kale. Blackheart tricks Kale and tries to make him as a member of his group of Spirits of Vengeance, promising Kale the power to rule in Hell alongside him. Ghost Rider double-crosses Blackheart, freeing the other Spirits of Vengeance and gaining rule over Blackheart's portion of Hell.