Which author created the 'Judge Dee' series?

The author who created the Judge Dee series is Robert van Gulik.

Van Gulik was a Dutch orientalist, diplomat, writer, and musician who adapted the character of Judge Dee from the traditional Chinese detective novel Di Gong An, or Celebrated Cases of Judge Dee. The fictional judge is based on the historical Tang-dynasty official Di Renjie, who lived approximately from 630 to 700.

After discovering an old copy of the Chinese novel in a Tokyo bookshop, van Gulik translated it into English. The translation was published in 1949, and he then began writing original Judge Dee mysteries. His stories combine Chinese gong’an detective-fiction traditions with techniques familiar to Western mystery readers.

A distinctive feature of the series is that Judge Dee often investigates three separate cases within one story. The books are set in an idealized Tang-dynasty China, where a county magistrate functions as both investigator and judge. The other listed authors created different detective figures, but none created the Judge Dee series.