He is depicted as the founder and headmaster of a magical academy for wizards that is attended by boys whose names begin with the letter "A".
[2] Kleks is depicted as a tall and eccentric man with a bushy beard, who wears a velvet frock coat over a waistcoat with numerous pockets.
[2] The character was partly based on Franciszek Fiszer, a Polish metaphysician and alchemist known to the literary circles of pre-World War II Warsaw.
[2] Kleks was portrayed by Piotr Fronczewski in three films based on the book series, each of which were directed by Krzysztof Gradowski [pl]: Akademia pana Kleksa (1983), Podróże pana Kleksa (1986) and Pan Kleks w kosmosie (1988).
Fronczewski also voiced the character in the 2001 animated film Tryumf pana Kleksa.