Klaus Groh (1936, Nysa) is a  German artist, musician and author, one of the most prominent members of the Mail Art movement.

Klaus Groh studied art education and art history at the Carl von Ossietzky University of Oldenburg. He led the Micro Hall Art Center and the Kleinkunstbühne Literaturium cabaret stage from 1971 to 2006, as well as the International Artists' Cooperation (IAC) from 1969 to 1990. He edited the IAC publication IAC-INFO, a Mail Art predecessor.

Groh compiled two important publications featuring numerous artists from Eastern Europe and ex-Yugoslavia - If I had a mind ... (Ich stelle mir vor ...): Conceptart, project art, 1971, and Aktuelle Kunst in Osteuropa – ČSSR, Jugoslawien, Polen, Rumänien, Sowjetunion, Ungarn, 1972. The publications feature contributions by over fifty artists who mostly worked in the fields of conceptual art. The first one included both Western and Eastern artists, while the second focused on the Eastern bloc and former Yugoslavia. Some of the included artists are Gabor Attalai, Imre Bak, Peter Bartoš, Slavko Bogdanović, Eugen Brikcius, Dalibor Chatrńy, Václav Cigler, Hugo Demartini, Braco Dimitrijević, Zbigniew Dłubak, Srečo Dragan, Grupa (Ǝ, Miklós Erdély, Stano Filko, Tibor Gáyor, Milan Grygar, György Jovánovics, Janez Kocijančić, JiřÍ Kocman, Grupa KôD, Stanislav Kolibal, Július Koller Gyula Konkoly, Jarosław Kozłowski, Andrzej Lachowicz, Natalia Lach-Lachowicz, Lászlo Lakner, Karel Malich, Milenko Matanović, Dóra Maurer, Alex Mlynárčik, Paul Neagu, Rudolf Němec, David Nez, Ladislav Novák, Lev Nussberg, Grupa OHO, Gyula Pauer, Attila Pálfalusi, Gérnecky, Marko Pogačnik, Bogdanka Poznanović, Andraž Šalamun, Rudolf Sikora, Jan Steklik, Petr Štembera, Tamás Szentjóby, Endre Tót, Goran Trbuljak, and others.

He is an essential connection between not only the East and the West in Europe, but Groh as well connected American Mail Art artists with the European ones. He was an active participant in the projects of other artists (such as Bogdanka Poznanović) and created many himself. His artistic practice, besides Mail Art, includes artist's book, collages, works on paper and others.