Ada in Vladimir Nabokov's "ada, or ardor: a family chronicle", has dreams as a young girl of being a lepidopterist on the fictional planet 'anti-terra'
The character Freddie Glegg in the movie The Collector (1965), directed by William Wyler and based on the novel by John Fowles.
The character of 'M' from the James Bond film series is revealed to be a lepidopterist, as evidenced in the film On Her Majesty's Secret Service. This can be seen when James Bond visits M at his country estate, upon which 007 finds the latter working with a specimen box.
Jack Mort, from Stephen King's: The Dark Tower II
Buffalo Bill, from Silence of the Lambs (Film)
The Monarch, principal antagonist from the television series The Venture Bros.
"Mr. Doe" & "Mr. Cardholder", two O.S.I. agents who intend to kill The Monarch (see above) in "The Lepidopterists," an episode from the third season of The Venture Bros.