Filmmaker Philip Kaufman had been in discussions with Marvel Studios to develop Namor: Sub-Mariner in 1997, and courted Sam Hamm to write the script in 1999, but the outing never materialized. Saban Entertainment became involved as a producing partner with Marvel, with a script written by Randall Frakes. By 2001, Namor was set up at Universal Pictures, who hired David Self to write a new script the following year. They hoped for filming to begin in 2003 for a mid-2004 release, but development stalled for two years until Chris Columbus entered talks to direct in July 2004 and the release date was subsequently moved to 2007. Columbus departed in 2005, and Universal replaced him with Jonathan Mostow in September 2006. In 2012, Marvel CCO Joe Quesada thought Namor's film rights had reverted to Marvel, but in August 2013 it was revealed by Marvel Studios President Kevin Feige that this was not the case, and the rights remained at Universal Pictures.
On June 3, 2014, Borys Kit confirmed that Marvel, not Universal Pictures, now had the Namor film rights. On July 18, 2014, Kevin Feige told IGN in an interview that the Namor film rights were not with Universal and Legendary Pictures, but he explained that there were a number of contracts and deals that needed to be sorted out. On June 2, 2016, Marvel Chief Creative Officer Joe Quesada told Kevin Smith on his podcast that the Namor rights were back with Marvel. On February 16, 2017, Production Weekly listed The Sub-Mariner as a project going into production. In April 2018, Feige stated in an interview with IGN that Namor's movie rights were "complicated" and in a similar situation to solo film rights for The Hulk, with Universal holding distribution rights. However, Namor will appear in a main role in 2022's Black Panther: Wakanda Forever, signaling that the rights issues have been cleared.