Axel Danielsson (15 December 1863, Värmland – 30 December 1899, Elsterberg, Germany) was a Swedish socialist agitator, journalist and writer. He was a prominent leader of the early Swedish Social Democratic Party. Danielsson retranslated Karl Marx's The Communist Manifesto into Swedish in 1886. Danielsson faced legal charges of blasphemy for a controversial article published in Hjalmar Branting's Social-Demokraten: the legal process culminated in the conviction of both men. Imprisoned in 1888, Danielsson celebrated the event by composing a pamphlet on the labour theory of value while serving out his sentence. During his imprisonment, his paper was managed by his then fiancée and later wife, Elma Danielsson.