* Although the family's surname was revealed as Wilkerson in the pilot episode, it was decided afterwards that they should not have a last name. A running joke on-set was that the family's last name was "Nolastname". This is officially confirmed in the final episode,
Malcolm in the Middle: Graduation (2006), when Francis drops his work pass, and his surname is briefly seen. Further confirmation can be seen when Malcolm is introduced to the stage for his speech. His last name is not heard, as the microphone screeches at the crucial moment, but you can read the announcer's lips clearly saying "Malcolm Nolastname".
