Carl Zeth "Zäta" Konstantin Höglund (29 April 1884 – 13 August 1956) was a leading Swedish communist politician, anti-militarist, author, journalist and mayor (finansborgarråd) of Stockholm (1940–1950).

At the May Day demonstration in 1903, Höglund and Fredrik Ström had an invitation to speak from the Social Democratic Party on a demand for 8-hour workdays.

They were curious of the homeland of the great French Revolution of 1789 and the city where their heroes Jean-Paul Marat, Georges Danton and Louis de Saint-Just had lived and fought.

When the Swedish conservatives made clear that they were prepared to subdue Norway by force, Zeth Höglund wrote the manifesto Down With Weapons!

The war was avoided, and Norway became independent, but, as a result of his anti-war agitation, Zeth Höglund was sentenced to six months in jail, which he served between the mid-summer and Christmas of 1906.

(The Right of Nations to Self-Determination) [2] In November 1912, Höglund, together with his Swedish friends Hjalmar Branting and Ture Nerman, attended the special emergency convention of the Socialist International, which had been summoned to Basel in Switzerland, due to the outbreak of the Balkan Wars.

At the convention, the leaders of all the European Socialist parties agreed to stand together internationally to prevent any future wars.

There the young Swedish socialist met Vladimir Lenin, Grigory Zinoviev, Vatslav Vorovsky, Karl Radek and Leon Trotsky: Zeth Höglund and Ture Nerman felt very close to the Russian Bolsheviks.

Lenin asked Höglund if the Swedish Socialist Youth Organization possibly could donate some much needed money to the Bolsheviks.

In April 1917, Lenin and other communists passed through Stockholm from the exile in Switzerland on their return trip to Russia after the February Revolution.

Lenin, who was greeted in Sweden by Otto Grimlund, Ture Nerman, Fredrik Ström and Carl Lindhagen, wanted to go and visit Höglund in jail.

Arrangements were made, but, due other meetings running over time and the Bolsheviks hurry to get back to Russia, Lenin's visit to Långholmen had to be cancelled.

On the same day of his release, Höglund held a speech in a park in Stockholm, massing thousands of people to hear him talk about peace, socialism and revolution.

In 1916, the left socialists launched their own newspaper, Politiken, in which they wrote and published many texts by Lenin, Zinoviev, Bukharin and Karl Radek.

Both Radek and Bukharin, who spent a lot of time in the neutral Sweden during the World War, had a great influence on the development of the Swedish Socialist Left.

Höglund wrote long texts for Politiken and managed to keep a great influence over the communist movement in Sweden from abroad.

On his way back to Sweden, Höglund also visited the Reds in Finland, which at the time was in the throes of the Finnish Civil War, which soon ended in White victory.

In March 1919, the founding congress of the Communist International (Comintern) took place in Russia, with Otto Grimlund representing the Swedish Socialist Left.

During the 2nd World Congress of the Comintern, which took place in Russia the summer of 1920, Zinoviev said, "Unfortunately Comrade Höglund and others who took part along with us in the founding of the Communist International are not here."