Back in 2016, the Dr Seuss estate won a preliminary court action against "Oh, The Places You'll Boldly Go!" a crowdfunded parody of Dr Seuss's "Oh the Places You'll Go!" and Star Trek, written by veteran Star Trek creator David "Tribble" Gerrold and illustrated by the comics giant Ty Templeton.
In 2017, Comicmix, the publisher, secured a partial legal victory, but the Seuss estate wasn't done — they have been litigating ever since, but now it appears the fight is done, and Comicmix has prevailed, with a Southern District of California judge declaring, in no uncertain terms, that the mashup was protected by fair use. The judgment is long and well-reasoned and comprehensive, and not the sort of thing that you'd expect to go on appeal to the Supreme Court (though who knows: the court has been terrible on copyright, and Ruth Bader Ginsburg never met an expansive theory of copyright she didn't like).
Timothy Geigner has published a detailed analysis of the judgment on Techdirt. It's quite an amazing read: the judge is very clear that no one is going to mistake Comicmix's parody for the Dr Seuss original, nor would they buy the parody as a substitute for Seuss, and the court is especially down on the Seuss estate's theory that the (terrible) decision in Oracle v Google means that mashups are illegal.
Examining the cover of each work, for example, Plaintiff may claim copyright protection in the unique, rainbow-colored rings and tower on the cover of Go! Plaintiff, however, cannot claim copyright over any disc-shaped item tilted at a particular angle; to grant Plaintiff such broad protection would foreclose a photographer from taking a photo of the Space Needle just so, a result that is clearly untenable under—and antithetical to—copyright law.
But that is essentially what Plaintiff attempts to do here. Instead of replicating Plaintiff's rainbow-ringed disc, Defendants drew a similarly-shaped but decidedly nonSeussian spacecraft—the USS Enterprise—at the same angle and placed a red-and-pink striped planet where the larger of two background discs appears on the original cover. See Duvdevani Decl. Ex. 31, ECF No. 115-11, at 450. Boldly's cover also features a figure whose arms and hands are posed similarly to those of Plaintiff's narrator and who sports a similar nose and eyes, but Boldly's narrator has clearly been replaced by Captain Kirk, with his light, combed-over hair and gold shirt with black trim, dark trousers, and boots.5 Id. Captain Kirk stands on a small moon or asteroid above the Enterprise and, although the movement of the moon evokes the tower or tube pictured on Go!'s cover, the resemblance is purely geometric. Id. Finally, instead of a Seussian landscape, Boldly's cover is appropriately set in space, prominently featuring stars and planets. Id. In short, "portions of the old work are incorporated into the new work but emerge imbued with a different character." See Mattel, Inc. v. Walking Mountain Prods., 353 F.3d 792, 804 (9th Cir. 2003).