Sonya Walger plays Desmond's off-island girlfriend Penny Widmore. Michael Bowen portrays the vengeful Other Pickett and William Mapother portrays the late Other, Ethan Rom. Blake Bashoff plays Alex's boyfriend Karl. Marsha Thomason plays Naomi Dorrit, who arrives on the Island. Andrew Divoff acts as the eye-patched Other Mikhail Bakunin and Nestor Carbonell acts as the ageless Other Richard Alpert. Tania Raymonde plays Alex, while Mira Furlan plays her mother Danielle Rousseau, who meets Alex for the first time since she was born. The third season featured numerous recurring guest stars.
In the Lost universe, the season takes place from November 28 to December 21, 2004. The third season continues the stories of a group of over 40 people who have been stranded on a remote island in the South Pacific, after their airplane crashed 68 days prior to the beginning of the season.
The third season of the American serial drama television series Lost commenced airing in the United States and Canada on October 4, 2006, and concluded on May 23, 2007.