A brilliant but impulsive tinkerer and former pupil of Cerebron. He first applies probability to make dragons real, and later disguises himself as an Echidnosaur to extort tribute after being denied payment by King Pfftius.

A methodical theoretician and close friend of Trurl. He embarks on the third sally to clear planets of dragons, tracks the Echidnosaur on Trufflandria, and discovers it is actually Trurl in a mechanical suit.

Instructor at the School of Higher Neantical Nillity who expounded the General Theory of Dragons and analytically discovered three distinct kinds of non-existent dragons.

The first scientist to quantize a dragon, detecting the dracotron particle and determining the coordinates of its tail.

A king against whom the constructors once sought revenge using a polypolice beast.

A traveling constructor suspected of artificially probabilizing dragons on various planets in order to extort exorbitant extermination fees from local rulers.

An emperor whose capital is swarming with virtual dragons; he offers his daughter's hand in marriage to Klapaucius for clearing them out.

A superstitious king who adheres to Pneumatological Dracolatry and uses bureaucratic red tape to avoid paying Trurl for slaying a local dragon.

A local official in a tattered tog who leads a procession carrying a heavy tribute of gold and perfume to the dragon, and recounts Trurl's visit to Klapaucius.

A local native who accompanies the court official up the mountain and corroborates the story of the stranger's visit.

A contributor to the dracological 'Cybr-Trurl-Klapaucius-Leech calculation'.

The inventor of the anticapita cannon, which exploits the contradictory nature of multi-headed dragons.