In A Taste For Death (London, 2014), Willie Garvin, handcuffed to a radiator and forced to hold up a bomb that will detonate as soon as he lowers it, wonders whether he can jerk the bomb from the wire to which it is attached and throw it through the shuttered window before it explodes, then thinks:
"Just as well send for Superman." (p. 99)
Here, Superman is clearly a fictitious character although there is no reference to any particular medium.
Later, when Willie claims to be one of only two men who have had sex hanging upside down from a trapeze, Modesty asks:
"'Who was the other bat-man?'" (p. 206)