Johannes Holzmann (30 October 1882 – 28 April 1914) was a German anarchist writer and activist who generally went by the pseudonym Senna Hoy.

Holzmann, born on 30 October 1882 in Tuchel, Prussia (now Tuchola, Poland), hailed from a bourgeois Jewish family.

Like many intellectuals around the turn of the century, he felt oppressed by the restrictive morals then reigning German society.

Among its writers were Else Lasker-Schüler, Herwarth Walden, Franz Pfemfert, Peter Hille, and Erich Mühsam and, at its best, it had a circulation of up to 10,000.

During this time, Holzmann wrote an article entitled "Die Homosexualität als Kulturbewegung" ("Homosexuality as a Cultural Movement").

He disagreed with the mainstream socialist movement, namely the Social Democratic Party of Germany (SPD), that viewed the repeal of Paragraph 175 as a minor issue.

He also opposed the SPD's tactic of forcefully outing gays, such as the steel magnate Friedrich Alfred Krupp, in order to bring about the repeal of Paragraph 175.

He also disagreed with many other German gay rights activists such as Adolf Brand who did not see their struggle as part of a wider movement.

Max Nettlau and Gustav Landauer, both well-known anarchists, criticized Der Kampf's sexual politics.

According to Walter Fähnders, a professor for German literature, it was because he wrote a short text that could interpreted as a depiction of a homosexual encounter.

At the same time and for the same reason, the government confiscated nude drawings by the artist Fidus and banned the poem "Die Freundschaft" ("Friendship") by Friedrich Schiller, one of the best known poets in German history.

Annoyed by this, he wrote a letter to the chief of the Berlin police, threatening to punch the next person he caught spying on him in the face.

[8] He opted for Russia, having reported on the 1905 Russian Revolution in Der Kampf, because he thought Europe's future depended on the outcome of revolutionary developments in that country.