Simon Baker ... Nick Fallin (67 episodes, 2001-2004)
Dabney Coleman ... Burton Fallin (67 episodes, 2001-2004)
Alan Rosenberg ... Alvin Masterson (67 episodes, 2001-2004)
Wendy Moniz ... Louisa 'Lulu' Archer (56 episodes, 2001-2004)
Raphael Sbarge ... Jake Straka (55 episodes, 2001-2004)
Charles Malik Whitfield ... James Mooney (33 episodes, 2001-2003)
Denise Dowse ... Judge Rebecca Damsen (32 episodes, 2001-2004)
Kathleen Chalfant ... Laurie Solt (27 episodes, 2001-2004)

The Guardian follows lawyer Nick Fallin\'s life after he is caught, convicted for drug use, and sentenced to 1,500 hours of community service. Fallin works off his sentence by working for the non-profit Children\'s Legal Services (CLS), while still continuing to work at Fallin & Associates in Pittsburgh. At Fallin & Associates, Nick Fallin works with several associates, including Jake Straka, his assistant Amanda Bowles, and for his father Burton Fallin. At CLS, Nick works with James Mooney, Lulu Archer, and for Alvin Masterson. This situation changes over the run of the series (as in CLS later became Legal Services of Pittsburgh (LSP) and other changes).