They are seeking monetary damages and apologies.
The king has hired Matthias Prinz, a star lawyer who specializes in cases involving celebrities and the media, to represent them in the case, filed in a Hamburg court.
Prinz has represented the royal family in previous cases involving the German press.
He also achieved notoriety for a case involving Princess Caroline of Monaco in which he successfully argued before the European Court that celebrities have a right not to be photographed.
The current suit involves publications by Bauer Verlagsgruppe from Hamburg and Essen-based WAZ, which publishes titles such as "Alles für die Frau", "Schöne Woche" and "Neue Post".
The case may not make it to trial, as cases are often settled ahead of time, something Prinz has done in past cases.
“Its too early to say whether we will be successful this time,” said Prinz.