In the 1969 film, Cogburn helped a headstrong 14-year-old girl named Mattie Ross (Kim Darby), along with Texas Ranger LaBoeuf (Glen Campbell), to track down Tom Chaney (Jeff Corey), the man who drunkenly killed her father.

Cogburn lived in Fort Smith, Arkansas, in the back of a Chinese dry-goods store, along with the proprietor, his friend and gambling buddy Chen Lee, and an orange tabby cat named after Confederate General Sterling Price for his entire life as a marshal.

In the 2010 film, while Cogburn demonstrated a ruthless attitude towards the criminals and fugitives he pursued, he was generally very fair with Mattie and was shown to have a distaste for what he viewed as unnecessary cruelty.

When the horse collapsed, he mercy-killed it with his revolver and then carried her a long distance in his arms to get her to a doctor, both saving her life and proving he really had the true grit Mattie thought he did.

Their greatest point of contention came during an argument about their military service during the American Civil War, during which Cogburn ended their agreement of splitting the reward on Tom Chaney when they brought him back to Texas when LaBoeuf insulted Capt Quantrill.

Twenty-five years after the Tom Chaney hunt, Maddie received a note from the Marshal with a flyer enclosed, saying Cogburn was traveling with a Wild West show and inviting her to come see him.

The novel was adapted into a 1969 film, True Grit, and from that a 1975 sequel entitled Rooster Cogburn was also produced, with Katharine Hepburn and a script loosely based on The African Queen set in the American frontier.