Walter Ernsting (13 June 1920 – 15 January 2005) was a German science fiction and fantasy author who mainly published under the pseudonym Clark Darlton.

After returning to Germany, Ernsting started to work as a translator for the British authorities in 1952 and came into contact with Anglo-American science fiction magazines.

Until the end of the 1960s, Ernsting worked as an editor for the club's magazine, Andromeda, and became an important figure in German science fiction fandom.

In 1958 he changed to the publishing house Moewig Verlag, Munich and its series for science fiction novels Terra and its magazine Galaxis.

In 1961, Ernsting, his colleague K. H. Scheer and other authors invented what would become the most successful German science fiction series, Perry Rhodan.