Ohser was born in Untergettengrün, nowadays an outlying centre of Adorf, in the Vogtland. When he was four years old, his family moved to Plauen (hence his choice of pseudonym). He completed his studies at the Akademie für Graphische Künste und Buchgewerbe in Leipzig in 1928, and began work at the Sächsische Sozialdemokratische Presse. In his work for such democratic magazines as Vorwärts, satirical representations of Josef Goebbels and Adolf Hitler earned him the enmity of the Nazis, and he was prohibited from practicing his trade (Berufsverbot). He continued to work under pseudonyms, and from 1940, began again to produce cartoons on political themes. He was arrested on charges of expressing anti-Nazi opinions (reichsfeindlicher Äußerungen).
On April 5, 1944 – the day before his trial – Ohser committed suicide in his cell, no doubt anticipating what befell the longtime friend and associate with whom he had been arrested, Erich Knauf (journalist, author and editor of the Volkszeitung für das Vogtland), who was executed weeks later.
In 1968 his ashes were interred in the central cemetery of his hometown, which took over responsibility for the grave's maintenance in 1988. The Städtische Galerie in Karlsruhe mounted an exhibition of his works in 2001.
He is also remembered with the E.O. Plauen prize for an outstanding living caricaturist.
Moreover, his "Vater und Sohn" characters have a statue in his hometown,
where the figures appear on storefronts and tram schedules