"Man of Steel, Woman of Kleenex" is a 1969 essay in which science fiction author Larry Niven details the problems that Superman would face in sexual intercourse and reproduction with a human woman, using arguments based on humorous reconciliation between physics, biology and the abilities of Kryptonians as presented in Superman comic books.
The title is a reference to the power and invulnerability indicated by Superman's epithet "Man of Steel", contrasting it with the relative fragility – like Kleenex brand facial tissue – of a human.
The hypothetical woman is referred to in the essay as "LL", the initials of three women Superman has been romantically involved with: Lois Lane, Lana Lang and Lori Lemaris.
[2] It was republished in the 1978 anthology SuperHeroes edited by Michel Parry and noted with a starburst on the cover: "SPECIAL BONUS FEATURE!
[4] It was published with softcore illustrations by classic Superman artist Curt Swan, with the character's identifying features and logo obscured, and conspicuous trademark/copyright disclaimers, in a 1995 issue of Penthouse Comix.