Dr. Abby Lockhart - ER

Main cast, played by Maura Tierney

Episode 6x12: Abby Road (Feb 3, 2000)
Episode 6x13: Be Still My Heart (1) (Feb 10, 2000)
Episode 6x14: All in the Family (2) (Feb 17, 2000)
Episode 6x15: Be Patient (Feb 24, 2000)
Episode 6x16: Under Control (Mar 23, 2000)
Episode 6x17: Viable Options (Apr 6, 2000)
Episode 6x18: Match Made in Heaven (Apr 13, 2000)
Episode 6x19: The Fastest Year (Apr 27, 2000)
Episode 6x20: Loose Ends (May 4, 2000)
Episode 6x21: Such Sweet Sorrow (May 11, 2000)
Episode 6x22: May Day (May 18, 2000)
Episode 7x01: Homecoming (Oct 12, 2000)
Episode 7x02: Sand and Water (Oct 19, 2000)
Episode 7x03: Mars Attacks (Oct 26, 2000)
Episode 7x04: Benton Backwards (Nov 2, 2000)
Episode 7x05: Flight of Fancy (Nov 9, 2000)
Episode 7x06: The Visit (Nov 16, 2000)
Episode 7x07: Rescue Me (Nov 23, 2000)
Episode 7x08: The Dance We Do (Dec 7, 2000)
Episode 7x09: The Greatest of Gifts (Dec 14, 2000)
Episode 7x10: Piece of Mind (Jan 4, 2001)
Episode 7x11: Rock, Paper, Scissors (Jan 11, 2001)
Episode 7x12: Surrender (Feb 1, 2001)
Episode 7x13: Thy Will Be Done (Feb 8, 2001)
Episode 7x14: A Walk in the Woods (Feb 15, 2001)
Episode 7x15: The Crossing (Feb 22, 2001)
Episode 7x16: Witch Hunt (Mar 1, 2001)
Episode 7x17: Survival of the Fittest (Mar 29, 2001)
Episode 7x18: April Showers (Apr 19, 2001)
Episode 7x19: Sailing Away (Apr 26, 2001)
Episode 7x20: Fear of Commitment (May 3, 2001)
Episode 7x21: Where the Heart Is (May 10, 2001)
Episode 7x22: Rampage (May 17, 2001)
Episode 8x01: Four Corners (Sep 27, 2001)
Episode 8x02: The Longer You Stay (Oct 4, 2001)
Episode 8x03: Blood, Sugar, Sex, Magic (Oct 11, 2001)
Episode 8x04: Never Say Never (Oct 18, 2001)
Episode 8x05: Start All Over Again (Oct 25, 2001)
Episode 8x06: Supplies and Demands (Nov 1, 2001)
Episode 8x07: If I Should Fall from Grace (Nov 8, 2001)
Episode 8x08: Partly Cloudy, Chance of Rain (Nov 15, 2001)
Episode 8x09: Quo Vadis? (Nov 22, 2001)
Episode 8x10: I'll Be Home for Christmas (Dec 13, 2001)
Episode 8x11: Beyond Repair (Jan 10, 2002)
Episode 8x12: A River in Egypt (Jan 17, 2002)
Episode 8x13: Damage Is Done (Jan 31, 2002)
Episode 8x14: A Simple Twist of Fate (Feb 7, 2002)
Episode 8x15: It's All In Your Head (Feb 28, 2002)
Episode 8x16: Secrets and Lies (Mar 7, 2002)
Episode 8x17: Bygones (Mar 28, 2002)
Episode 8x18: Orion in the Sky (Apr 4, 2002)
Episode 8x19: Brothers & Sisters (Apr 25, 2002)
Episode 8x20: The Letter (May 2, 2002)
Episode 8x21: On the Beach (May 9, 2002)
Episode 8x22: Lockdown (May 16, 2002)
Episode 9x01: Chaos Theory (Sep 26, 2002)
Episode 9x02: Dead Again (Oct 3, 2002)
Episode 9x03: Insurrection (Oct 10, 2002)
Episode 9x04: Walk Like a Man (Oct 17, 2002)
Episode 9x05: A Hopeless Wound (Oct 31, 2002)
Episode 9x06: One Can Only Hope (Nov 7, 2002)
Episode 9x07: Tell Me Where It Hurts (Nov 14, 2002)
Episode 9x08: First Snowfall (Nov 21, 2002)
Episode 9x09: Next of Kin (Dec 5, 2002)
Episode 9x10: Hindsight (Dec 12, 2002)
Episode 9x11: A Little Help from My Friends (Jan 9, 2003)
Episode 9x12: A Saint in the City (Jan 16, 2003)
Episode 9x13: No Good Deed Goes Unpunished (Jan 30, 2003)
Episode 9x14: No Strings Attached (Feb 6, 2003)
Episode 9x15: A Boy Falling Out of the Sky (Feb 13, 2003)
Episode 9x16: A Thousand Cranes (Feb 20, 2003)
Episode 9x17: The Advocate (aka Side Effects) (Mar 13, 2003)
Episode 9x18: Finders Keepers (Apr 3, 2003)
Episode 9x19: Things Change (Apr 24, 2003)
Episode 9x20: Foreign Affairs (May 1, 2003)
Episode 9x21: When Night Meets Day (May 8, 2003)
Episode 9x22: Kisangani (May 15, 2003)
Episode 10x01: Now What? (Sep 25, 2003)
Episode 10x02: The Lost (Oct 2, 2003)
Episode 10x03: Dear Abby (Oct 9, 2003)
Episode 10x04: Shifts Happen (Oct 23, 2003)
Episode 10x05: Out of Africa (Oct 30, 2003)
Episode 10x06: The Greater Good (Nov 6, 2003)
Episode 10x07: Death and Taxes (Nov 13, 2003)
Episode 10x08: Freefall (Nov 20, 2003)
Episode 10x09: Missing (Dec 4, 2003)
Episode 10x10: Makemba (Dec 11, 2003)
Episode 10x11: Touch and Go (Jan 8, 2004)
Episode 10x12: NICU (Jan 15, 2004)
Episode 10x13: Get Carter (Feb 5, 2004)
Episode 10x14: Impulse Control (Feb 12, 2004)
Episode 10x15: Blood Relations (Feb 19, 2004)
Episode 10x16: Forgive and Forget (Feb 26, 2004)
Episode 10x17: The Student (Apr 1, 2004)
Episode 10x18: Where There's Smoke (Apr 8, 2004)
Episode 10x19: Just a Touch (Apr 22, 2004)
Episode 10x20: Abby Normal (Apr 29, 2004)
Episode 10x21: Midnight (May 6, 2004)
Episode 10x22: Drive (May 13, 2004)
Episode 11x01: One for the Road (Sep 23, 2004)
Episode 11x02: Damaged (Oct 7, 2004)
Episode 11x03: Try Carter (Oct 14, 2004)
Episode 11x04: Fear (Oct 21, 2004)
Episode 11x05: An Intern's Guide to the Galaxy (Nov 4, 2004)
Episode 11x06: Time of Death (Nov 11, 2004)
Episode 11x07: White Guy, Dark Hair (Nov 18, 2004)
Episode 11x08: A Shot in the Dark (Dec 2, 2004)
Episode 11x09: 'Twas the Night (Dec 9, 2004)
Episode 11x10: Skin (Jan 13, 2005)
Episode 11x11: Only Connect (Jan 20, 2005)
Episode 11x12: The Providers (Jan 27, 2005)
Episode 11x13: Middleman (Feb 3, 2005)
Episode 11x14: Just As I Am (Feb 10, 2005)
Episode 11x15: Alone in a Crowd (Feb 17, 2005)
Episode 11x16: Here and There (Feb 24, 2005)
Episode 11x17: Back in the World (Mar 24, 2005)
Episode 11x18: Refusal of Care (Apr 21, 2005)
Episode 11x19: Ruby Redux (Apr 28, 2005)
Episode 11x20: You Are Here (May 5, 2005)
Episode 11x21: Carter est Amoureux (May 12, 2005)
Episode 11x22: The Show Must Go On (May 19, 2005)
Episode 12x01: Cañon City (Sep 22, 2005)
Episode 12x02: Nobody's Baby (Sep 29, 2005)
Episode 12x03: Man with No Name (Oct 6, 2005)
Episode 12x04: Blame It on the Rain (Oct 13, 2005)
Episode 12x05: Wake Up (Oct 20, 2005)
Episode 12x06: Dream House (Nov 3, 2005)
Episode 12x07: The Human Shield (Nov 10, 2005)
Episode 12x08: Two Ships (Nov 17, 2005)
Episode 12x09: I Do (Dec 1, 2005)
Episode 12x10: All About Christmas Eve (Dec 8, 2005)
Episode 12x11: If Not Now (Jan 5, 2006)
Episode 12x12: Split Decisions (Jan 12, 2006)
Episode 12x13: Body and Soul (Feb 2, 2006)
Episode 12x14: Quintessence of Dust (Feb 9, 2006)
Episode 12x15: Darfur (Mar 2, 2006)
Episode 12x16: Out on a Limb (Mar 16, 2006)
Episode 12x17: Lost in America (Mar 23, 2006)
Episode 12x18: Strange Bedfellows (Mar 30, 2006)
Episode 12x19: No Place to Hide (Apr 27, 2006)
Episode 12x20: There Are No Angels Here (May 4, 2006)
Episode 12x21: The Gallant Hero and the Tragic Victor (May 11, 2006)
Episode 12x22: Twenty-One Guns (May 18, 2006)
Episode 13x01: Bloodline (Sep 21, 2006)
Episode 13x02: Graduation Day (Sep 28, 2006)
Episode 13x03: Somebody to Love (Oct 5, 2006)
Episode 13x04: Parenthood (Oct 12, 2006)
Episode 13x05: Ames v. Kovac (Oct 19, 2006)
Episode 13x06: Heart of the Matter (Nov 2, 2006)
Episode 13x07: Jigsaw (Nov 9, 2006)
Episode 13x08: Reason to Believe (Nov 16, 2006)
Episode 13x09: Scoop and Run (Nov 23, 2006)
Episode 13x10: Tell Me No Secrets... (Nov 30, 2006)
Episode 13x11: City of Mercy (Dec 7, 2006)
Episode 13x12: Breach of Trust (Jan 4, 2007)
Episode 13x13: A House Divided (Jan 11, 2007)
Episode 13x14: Murmurs of the Heart (Feb 1, 2007)
Episode 13x15: Dying Is Easy (Feb 8, 2007)
Episode 13x16: Crisis of Conscience (Feb 15, 2007)
Episode 13x17: From Here to Paternity (Feb 22, 2007)
Episode 13x18: Photographs & Memories (Apr 12, 2007)
Episode 13x19: Family Business (Apr 19, 2007)
Episode 13x20: Lights Out (Apr 26, 2007)
Episode 13x21: I Don't (May 3, 2007)
Episode 13x22: Sea Change (May 10, 2007)
Episode 13x23: The Honeymoon Is Over (May 17, 2007)
Episode 14x01: The War Comes Home (Sep 27, 2007)
Episode 14x02: In a Different Light (Oct 4, 2007)
Episode 14x03: Officer Down (Oct 11, 2007)
Episode 14x04: Gravity (Oct 18, 2007)
Episode 14x05: Under the Influence (Oct 25, 2007)
Episode 14x06: The Test (Nov 1, 2007)
Episode 14x07: Blackout (Nov 8, 2007)
Episode 14x08: Coming Home (Nov 15, 2007)
Episode 14x09: Skye's the Limit (Nov 29, 2007)
Episode 14x10: 300 Patients (Dec 6, 2007)
Episode 14x11: Status Quo (Jan 3, 2008)
Episode 14x12: Believe the Unseen (Jan 10, 2008)
Episode 14x13: Atonement (Jan 17, 2008)
Episode 14x14: Owner of a Broken Heart (Apr 10, 2008)
Episode 14x15: ...As the Day She Was Born (Apr 17, 2008)
Episode 14x16: Truth Will Out (Apr 24, 2008)
Episode 14x17: Under Pressure (May 1, 2008)
Episode 14x18: Tandem Repeats (May 8, 2008)
Episode 14x19: The Chicago Way (May 15, 2008)
Episode 15x01: Life After Death (Sep 25, 2008)
Episode 15x03: The Book of Abby (Oct 16, 2008)

Guest cast, played by Maura Tierney

Episode 6x08: Great Expectations (Nov 25, 1999)