TKKG is a popular book and radio drama series for children and teenagers in Germany. They were initially written by Rolf Kalmuczak under the pseudonym Stefan Wolf, after his death the stories were continued by different authors. The abbreviation TKKG stands for the four main characters: Tim, Karl, Klößchen and Gaby. The stories are about exciting adventures that the TKKG team experiences together. Tim is the leader of the gang, Karl the intelligent technology freak, Klößchen the somewhat overweight and always hungry best friend of Tim and Gaby is the only female character, a sporty, brave and smart student.

The individual stories are about crimes that the TKKG team has to solve, such as thefts, extortions and kidnappings. The action usually takes place in a small German town or in the countryside, and the friends are often involved in dangerous situations that they have to overcome with courage and cleverness.

The TKKG stories have a large fan base and have been filmed and adapted several times since their release in the 1980s. Suitable for children aged 8 and up, the stories offer exciting entertainment while conveying moral messages and values such as friendship, justice and courage.