What is Joker's canon name?
Could you please clarify what you mean by "Joker's canon name"? Are you referring to the character from the Batman universe, the Joker? If so, it's important to note that the Joker's real name has varied across different media and interpretations. In the original comics, his true identity was never definitively revealed. However, in some adaptations, such as the Christopher Nolan-directed Dark Knight trilogy, the Joker is portrayed as a character named Jack Napier who undergoes a transformation into the Joker. But, to answer your question directly, there is no universally accepted "canon" name for the Joker in the Batman universe.