The 2002 film, Red Dragon is considered to be a prequel to The Silence of the Lambs and Hannibal. In these films, Dr. Hannibal Lecter's name is spelled "Hannibal Lecter". Per the script for Red Dragon.
As Graham enters, he passes a brass plaque that reads "HANNIBAL LECTER, M.D./Psychiatric Consultations".
The 1986 film Manhunter was the original film adapted from the novel of the same name. This film has the same characters as Red Dragon, most notably Hannibal Lecter. However, Hannibal Lecter's name is spelled "Hannibal Lecktor" in this film. There is a newspaper article shown in the film that shows the spelling this way and it is also spelled this way in the credits and the script:
I want you to help me, Dr. Lecktor.
Is there any explanation from filmmakers on the different spelling of Dr. Lecter's last name? Why is Hannibal Lecter's last name spelled differently in these movies if he is the exact same character?