Roy Lichtenstein (1923-1997) "Sleeping Girl" - $44.9 million
Artist: Famous American Pop Artist and major ben-day dot fan
Artwork: Part of a series of sexy comic book-inspired images Lichtenstein created in 1964.
Auction: Sotheby's Contemporary Art Evening Sale (May 2012)
Here's a link to an in-depth Attempted Bloggery post about the original source -- DC artist Tony Abruzzo's panel from the Girl's Romances #105 December 1964 story, "Don't Kiss Me Again."