"Stefan Wolf" is the best-known pseudonym of German author Rolf Kalmuczak (1938–2007), who wrote the long-running youth crime series TKKG under this name from 1979 onward. Kalmuczak used more than 100 pseudonyms over his career and published roughly 160 youth books alongside crime novels, screenplays and short fiction; as "Stefan Wolf" alone, the TKKG series sold more than 14 million copies in print and around 30 million audio recordings. Following Kalmuczak's death in 2007, the TKKG series has continued under the same "Stefan Wolf" name, written by other authors.
