The first incarnation of Baron Blood, John Falsworth, first appeared in The Invaders #7 (July 1976), who has been part of the superhero Captain America's rogues gallery since World War II.

Dan Slott and Rita Fagiani featured Crichton and his mother again in "Young Blood" for Marvel Comics Presents #89 (November 1991); in the story, he is kidnapped in an attempt to steal the secret of youth from the recently rejuvenated Lady Jacqueline.

Falsworth appears as a supporting character in Nicholas Vince and Mark Buckingham's four-issue Mortigan Goth: Immortalis (September 1993 – October 1994) miniseries for Marvel UK; the story reveals in flashback that while staying at Falworth Manor during World War II under his original assumed identity, he turned the spurned lover of the titular anti-hero into a vampire.

Smith's New Invaders #4-5 (January – February 2005); in which in she traps Lady Jacqueline using an image of Crichton and feeds her blood to their newborn vampiric son, while Falsworth made a brief appearance in Steve Niles and Rafael Garres's story "Self-Made Monster" for Amazing Fantasy #17 (March 2006); in which a flashback shows him taking revenge against biochemist Michael Morbius for polluting the vampire bloodline.

[3] When the family fortune is left to his older brother James, John Falsworth leaves England to pursue an interest of his - vampire lore.

Adopting the alias of "Baron Blood" (German: Freiherr Blut), the character allies with Germany during World War I and without either party realizing the identity of the other, battles his own brother, who is now the English hero Union Jack.

[3] The character reappears during World War II in his false persona, and once again aids Germany, with Nazi technology helping him to reduce his susceptibility to sunlight (a major vampire weakness).

[3] Baron Blood reappears when Japanese soldiers sent by the spy Lady Lotus find the cavern and attempt to resurrect the character.

Blood travels to the United States of America and, after a brief skirmish with the Invaders, joins the Nazi team the Super-Axis for a final battle with the heroes.

[9] During the "Opening Salvo" part of the "Secret Empire" storyline, Baron Blood is recruited by Helmut Zemo to join the Army of Evil.

[13] The storyline "The Book of the Vishanti: Curse of the Darkhold" in the title Doctor Strange: Sorcerer Supreme features a second version of the character.

[14] When a still-inexperienced Doctor Strange attempts to resurrect his dead brother Victor with a spell from the Book of the Vishanti, it revives him as a vampire.

Kenneth Crichton, the son of Jacqueline Falsworth and a sufferer of the medical condition anemia, is estranged from his family after refusing to adopt the identity of Union Jack, deeming his close friend Joey Chapman to be a better choice.

[20] The first Baron Blood possessed all the powers of a vampire, including superhuman strength and durability; hypnotism and the ability to command bats, wolves, dogs, and rodents.

Weaknesses included vulnerability to sunlight, garlic, and silver; the presence of religious symbols; decapitation and a wooden stake through the heart.

Courtesy of Nazi science, Blood received treatment that allowed him activity in sunlight, at least for some length of time, although this also removed his shapeshifting abilities.

[27] Baron Blood appears in Marvel Disk Wars: The Avengers, voiced by Kazunari Tanaka in the original Japanese version and by Steve Kramer in the English dub.