Lex

Lex was a fictional character who appeared in the Superman comic book series.

In an issue of the comic read by the Twelfth Doctor, Lex was in bed recovering from kryptonite poisoning under the care of Dr Kelley. The radioactivity of his kryptonite signet ring had left him without his right hand. (TV: The Return of Doctor Mysterio)

Behind the scenes

 * Although we never find out his last name in The Return of Doctor Mysterio, in the real world this is of course Lex Luthor.
 * Lex Luthor appeared as an antagonist in Lego Dimensions.