Solf J. Kimblee, also known as the Crimson Alchemist or Red Lotus Alchemist, is a former State Alchemist from the Fullmetal Alchemist manga. His background is rooted in the brutal Ishval Civil War, where he served as a soldier and earned his fearsome reputation. During that conflict, he was known for his ruthless efficiency and lack of remorse, killing thousands of Ishvalan men, women, and children without hesitation. He was given an imperfect Philosopher's Stone to amplify his abilities, and with it, he killed the family of the man who would later become known as Scar, inflicting the distinctive cross-shaped scar on Scar's face. After the war, rather than surrender the Stone to his superiors, Kimblee killed several of his own officers to keep it, an act for which he was imprisoned.

Kimblee's personality is a study in contradictions. He is a polite, soft-spoken, and well-dressed individual who often wears a pristine white suit and fedora, presenting a facade of gentlemanly civility. Beneath this calm exterior, however, he is a remorseless psychopath and a sadist who genuinely delights in the sight of blood, death, and the sound of explosions. He views mass murder not as a grim duty but as a form of personal fulfillment. This bizarre combination of affability and cruelty defines his interactions; he is respectful and honest even with his enemies, yet he will kill them without a second thought. His personal philosophy is a unique form of social Darwinism, which he refers to as "survival of the fittest." He holds deep contempt for hypocrisy and cowardice, and paradoxically, he respects individuals who adhere strongly to their own principles, whether those principles align with his or not. He criticized State Alchemists like Roy Mustang and Riza Hawkeye for their guilt over killing in Ishval, arguing that they willingly became soldiers and must accept that role.

Kimblee's motivations are driven by a detached, philosophical curiosity. He does not side with the homunculi out of loyalty or a desire for power, but because he wants to observe the outcome of the coming conflict between humans and these artificial beings. He allies with Führer King Bradley and his homunculi out of a desire to see which side the world will ultimately choose, viewing the entire struggle as a grand experiment in natural selection. He is not invested in the homunculi's plan to create a nationwide Philosopher's Stone for its own sake; rather, he sees his role in carving a "crest of blood" for the transmutation circle as another opportunity to witness and participate in a massive, transformative event. His primary goal is simply to witness the world change and to confirm his belief in the supremacy of those who act on their convictions.

In the story, Kimblee serves as a major antagonist, particularly during the arc set in the northern region of Briggs. Released from prison by the homunculi, he is tasked with hunting down Scar and the fugitive alchemist Dr. Marcoh. To force the Elric brothers to cooperate, he takes their friend Winry Rockbell hostage, demonstrating his pragmatic and manipulative nature. His role is to act as a direct, intelligent, and physically dangerous obstacle for Edward Elric, Scar, and the soldiers of Fort Briggs. His presence creates a tense cat-and-mouse game through the snowy northern terrain.

Key relationships define much of his role. His most significant adversarial relationship is with Scar, whom he grievously wounded years prior. Scar harbors a deep, personal hatred for Kimblee, while Kimblee initially does not even remember him, demonstrating the callousness with which he views his victims, though he does make a point of remembering faces in general. He shares a working relationship with the homunculus Pride, the first and most powerful of the homunculi. Pride is one of the few beings Kimblee seems to regard as an equal or superior, though this alliance is purely transactional. He also has a complex interaction with Edward Elric, whom he respects for the young alchemist's resolve not to kill, even as he dismisses it as naive.

Kimblee's development, or lack thereof, is a key aspect of his character. He remains utterly consistent in his beliefs and demeanor until his death. He does not experience a redemption arc or a crisis of conscience. However, his final act serves as a powerful testament to his unwavering philosophy. After being fatally wounded by the chimera Heinkel, a dying Kimblee is absorbed by Pride, who consumes his body and soul to add to the Stone that powers him. Despite being trapped in a vortex of thousands of agonized souls within Pride, Kimblee's exceptional willpower and his perverse delight in the suffering around him allow him to retain his individuality. When Pride, desperate to survive, abandons his own pride by attempting to possess Edward Elric's body, Kimblee is disgusted by this hypocrisy. He rebels from within, interfering with Pride's ability to control Edward's form and ultimately buying Edward the time needed to defeat the homunculus. He then vanishes with a tip of his hat, his final action being a rejection of cowardice and a validation of his own twisted code of honor.

Kimblee's notable abilities center on his unique form of explosive alchemy. He has transmutation circles tattooed on his palms: a sun on his right and a moon on his left. By pressing his hands together to form a hexagram, he can transmute any matter he touches into an explosive bomb. The scale of his explosions is massively amplified when he uses a Philosopher's Stone, allowing him to bypass the Law of Equivalent Exchange and create devastating blasts that can level buildings and terrain. He is cunning, intelligent, and has a photographic memory, which makes him a formidable strategist as well as a combatant. His physical resilience is also notable, allowing him to continue functioning after being impaled by Scar. Ultimately, it is not his explosive alchemy but his unbreakable, amoral will that proves to be his most defining and, for his enemies, most dangerous trait.