Graphic novel icon Frank Miller claims his ex-wife's being super sketchy by hiding and secretly selling some of his famous drawings ... this according to a new lawsuit.
According to new legal docs obtained by TMZ ... Frank claims Lynn Varley's illegally holding onto a slew of sketches he drew as references for the final illustrations for his comics and graphic novels.
What's more, Frank claims Varley's already sold some of his sketches through her art dealer --- offering them for sale to "under the table" to collectors. Literally, under the table.
In docs, he claims one of Varley's reps kept Miller's sketches in a binder under a table at this year's Comic-Con in San Diego. Miller claims when a potential buyer would ask about the sketches, the rep would pull out a separate binder from under the vendor's table.
Frank claims Varley got some of his work as part of their divorce settlement, but also insists HE is the rightful owner of others she's been secretly selling. He's suing for her to turn over the sketches and wants a full accounting of what she's already hocked and for how much.
Miller, of course, is the famed comic book writer and artist behind "Sin City," "The Dark Knight Returns" and "300."