Marvin "Marv" is a fictional character in the graphic novel series Sin City, created by Frank Miller. In the 2005 film adaptation and its 2014 sequel, he is played by Mickey Rourke. He first appears in The Hard Goodbye and follows with appearances in A Dame to Kill For, Just Another Saturday Night, and Silent Night. He makes a brief cameo in Blue Eyes.

Sin City is a series of neo-noir comics by American comic book writer-artist Frank Miller. The first story originally appeared in Dark Horse Presents Fifth Anniversary Special, and continued in Dark Horse Presents #51–62 from May 1991 to June 1992, under the title of Sin City, serialized in thirteen parts. Several other stories of variable lengths have followed. The intertwining stories, with frequently recurring characters, take place in Basin City.