Which prominent Jacobin edited the newspaper L'Ami du Peuple and was assassinated in a bathtub?

The prominent Jacobin who edited the newspaper L'Ami du Peuple and was famously assassinated in a bathtub is Jean-Paul Marat. He played a significant role during the French Revolution as a radical journalist and political theorist. Marat used his publication to promote revolutionary ideas and to advocate for the rights of the poor and marginalized, often employing sensationalist rhetoric to rally popular support for the revolutionary cause. His assassination in 1793 by Charlotte Corday, who opposed his violent tactics and influence, made him a martyr for the revolutionary movement and solidified his legacy in revolutionary iconography. This context highlights Marat's crucial influence in revolutionary circles, illustrating why he is the correct answer to the question.