ABC airs the 48th episode of the J.J. Abrams-produced series Lost, opening the show’s much-anticipated third season. Deep analysis of clues of the show’s backstory has now become a popular pastime, not simply an internet phenomenon. Elizabeth Mitchell (V), Michael Emerson, and Henry Ian Cusick join as series regulars; William Mapother and Brett Cullen guest star. 
ABC airs the 49th episode of the J.J. Abrams-produced series Lost. Byron Chung guest stars.
ABC airs the 50th episode of the J.J. Abrams-produced series Lost. Ian Somerhalder reprises his first-season role as Boone; Kiele Sanchez and Rodrigo Santoro are introduced as new regulars Nikki and Paulo, a move much-derided by the show’s rapidly growing fandom.
ABC airs the 51st episode of the J.J. Abrams-produced series Lost. Kim Dickens guest stars.
ABC airs the 52nd episode of the J.J. Abrams-produced series Lost.
ABC airs the 53rd episode of the J.J. Abrams-produced series Lost. Nathan Fillion (Firefly) guest stars. The series will return in 2007, with the remainder of the third season airing without interruption.
ABC airs the 54th episode of the J.J. Abrams-produced series Lost. Guest star Nestor Carbonell makes his first appearance as Richard Alpert.
ABC airs the 55th episode of the J.J. Abrams-produced series Lost. Alan Dale (Angel, Torchwood) and Fionnula Flanagan guest star.
ABC airs the 56th episode of the J.J. Abrams-produced series Lost. M.C. Gainey and Bai Ling guest star.
ABC airs the 57th episode of the J.J. Abrams-produced series Lost. Mira Furlan (Babylon 5) and Cheech Marin (of Cheech & Chong fame) guest star.
ABC airs the 58th episode of the J.J. Abrams-produced series Lost. Mira Furlan (Babylon 5) and Andrew Divoff guest star.
ABC airs the 59th episode of the J.J. Abrams-produced series Lost. Mira Furlan (Babylon 5) and Andrew Divoff guest star.
ABC airs the 60th episode of the J.J. Abrams-produced series Lost. Mira Furlan (Babylon 5) and Nestor Carbonell guest star.
ABC airs the 61st episode of the J.J. Abrams-produced series Lost. Billy Dee Williams (The Empire Strikes Back) guest stars in an episode devoted to narratively disposing of much-derided new regular characters Nikki and Paulo.
ABC airs the 62nd episode of the J.J. Abrams-produced series Lost. Kim Dickens guest stars.
ABC airs the 63rd episode of the J.J. Abrams-produced series Lost. Andrew Divoff and Nestor Carbonell guest star.
ABC airs the 64th episode of the J.J. Abrams-produced series Lost.
ABC airs the 65th episode of the J.J. Abrams-produced series Lost. Byron Chung and Andrew Divoff guest star.
ABC airs the 66th episode of the J.J. Abrams-produced series Lost. Mira Furlan (Babylon 5) and Nestor Carbonell guest star.
ABC airs the 67th episode of the J.J. Abrams-produced series Lost. Andrew Divoff and Nestor Carbonell guest star.
ABC airs the 68th episode of the J.J. Abrams-produced series Lost. Mira Furlan (Babylon 5) and Nestor Carbonell guest star.
ABC airs the 69th episode of the J.J. Abrams-produced series Lost, ending the show’s third season. Mira Furlan (Babylon 5), Andrew Divoff, and Nestor Carbonell guest star in a season finale that turns the series’ long-established format on its ear by introducing flash-forwards to a time when the characters have already escaped the island.