Originally Left Communism was a tendency within the Communist International most specifically within its German, Dutch, Bulgarian and Italian sections. Sylvia Pankhursts theoretically more amorphous group the Communist Party British Section of the Third International also identified with this left. Alongside these tendencies there the Italian tendency identified with Amadeo Bordiga is also recognised as being a Left Communist tendency. These assorted groups were polemicized with by Lenin in his booklet "Leftwing Communism, An Infantile Disorder".
Politically there was little in common between them. However all opposed what they called 'Frontism'. the tactic endorsed by Lenin of the Communists seeking tactical agreements with reformist parties in pursuit of a definite, usually defensive, goal. The Dutch-German tendency, the Bulgarians and British also opposed standing in elections which they denounced as parliamentarism. Similarly the Italians supported the Right of Nations to Self Determination which the Dutch-Germans rejected.
The Left Communists were expelled from the KPD and they formed the Communist Workers Party KAPD. Similar parties were formed in the Netherlands, Bulgaria and Britain. The KAPD rapidly lost most of its members and was reduced to being a small sect riven by factional differences until its eventual collapse. However some of its militants had been instrumental in organising factory based unions like the AAUD and AAUD-E. The latter being opposed to separate party organisation.
The leading theoreticians of the KAPD had developed a new series of ideas based on their opposition to party organisation and conception of the Bolshevik led revolution in Russia as having been a bourgeois revolution. Their leading figures were Anton Pannekoek and Herman Gorter, as well as Otto Rühle who had never been a member of the KAPD. Another leading theoretician of Council Communism was Paul Mattick who emigrated to the USA. A minor figure in the Council Communist movement in the Netherlands was Marinus van der Lubbe whose name is attached to the burning of the Reichstag in 1933.