"I Do" is the sixth episode of the third season of Lost, and the 55th episode overall. It aired on November 8, 2006, on ABC. The episode was written by Damon Lindelof and Carlton Cuse and directed by Tucker Gates. The character of Kate Austen (Evangeline Lilly) is featured in the episode's flashbacks, where her brief marriage to a police officer, Kevin Callis (Nathan Fillion), is shown.