She was portrayed by Katey Sagal who is best known for her roles such as Peggy Bundy from Married With Children, PAT in Smart House, and Leela from Futurama.
Gemma was born in Oregon in 1957 and became a resident of Charming, California, after her father, Rev. Madock accepted a position in Charming United Church. She met John Teller, a Vietnam War veteran and founder of the Sons of Anarchy Motorcycle Club, in 1978, after leaving home in 1975. Two months after meeting JT Teller, she became pregnant. She had two children:'Jax Teller' born in 1978 and Thomas Teller born in 1984. Gemma has a genetic heart disorder which she passed on to her children, from which Thomas died in 1990. John was hit by a semi-truck and died in 1993. Teller's death was orchestrated by Clay Morrow who was manipulated by Gemma to this end. Gemma married John's friend Clay Morrow, after carrying on an open affair with him for quite some time. She is of Irish (father) and Russian Jewish (mother) descent.
From the time she left Charming in 1975 until she met JT Teller, she became best friends with Luann, who was involved in the porn industry. It is not revealed whether Gemma was involved in porn herself. She supports Luann strongly. Luann was her Maid of Honor at her wedding to JT in 1978. She lives in the same house she shared with John, at 5024 Sandy Creek Rd. in Charming. Gemma Teller Morrow is the queen of Charming (a fictional town in Northern CA that's supposed to be between Lodi and Stockton) and the matriarch of the Sons of Anarchy. A Machiavellian schemer and expert in psychological manipulation, Gemma is extremely protective of her son and grandsons.
She longs for the day when Jax will, in her eyes, be ready to assume control of SAMCRO, ensuring the organization's survival for another generation. She adores her husband, Clay, and does her best to make things work out in his favor. Many of SAMCRO's plans succeed because of Gemma's quiet intervention. Up until her death in the penultimate episode of Season 7 (as well as the series), Gemma was one of two characters (along with Jax) to appear in every episode.
Symbols of Gemma's driving need for control appear throughout the series. For example, she keeps birds as pets because she can control and cage them, yet shows them great care and affection, much like her family. Another symbol of Gemma's control is the caged playground, reminiscent of her birdcages, at the Sons of Anarchy headquarters. Her grandchildren play under her control at the playground. Her need for control shows an obsessive hatred of clutter and disorder. Her contempt for Wendy, Jackson's ex-wife, is increased by Wendy's slovenliness and lack of self-control. At first, she hates Tara until she feels she controls her. Tara allows Gemma to believe she controls Tara. Tara even mimics Gemma's hairstyle and clothing, in order to be accepted by Gemma. However, when Tara begins turning against SAMRCO and Gemma, Gemma realizes that she never had true control of Tara. At this point, Tara tells Gemma, "I am smarter than you." Gemma's "love" for Tara turns to hatred because she realizes Tara has actually been controlling and manipulating Gemma. Gemma's agony at losing control of her Tara and her grandchildren result in tragedy.
Gemma begins the series as a good mom that does everything to protect is son Jax, and that includes the destruction of Wendy, his ex-wife. Wendy is pregnant by Jax, but her drug addiction results in the premature birth of her son, Abel. Gemma is outraged by Wendy's irresponsibility that almost results in the death of her grandson. However, Gemma coldly manipulates Wendy to kill herself in the hospital by handing her a syringe loaded with methadone. However, Wendy, who has failed in every of her life, fails to kill herself.
Tara (the ex-girlfriend and true love of Jax) has returned to Charming as a surgeon working in the same hospital where Wendy and Abel are patients. Her motivation for her comeback to Charming seems to be that she is running away from something, but also running back to Jax. Gemma is threatened by Tara's love for Jax because she knows she will lose control of him. She tried to intimidate Tara, but realizes that she is formidable adversary. In fact, Tara courageously confronts Gemma. Tara coldly says, "You still think you can say or do anything you want in this town, don't you? But everything comes around Gemma, no one is untouchable."
Donna (the wife of Opie, a important member of the club) try to convince his husband to get out of the SAMCRO, but Gemma manipulates Donna and stop her. One of the new guys on the club is smitten by Gemma. Gemma, ever the controlling opportunist, uses his infatuation in order to manipulate him into doing her bidding. Meanwhile, Tara grows closer to Jax and rekindles their romantic relationship.
Meanwhile, Gemma tries to push Wendy out of her family's lives. She aids Jax in obtaining custody of Abel in order to protect him from Wendy.
Gemma argues with Clay Morrow, provoking him into throwing a rock at her car. In turn, she dares kick over Clay's motorcycle. She responds to Clay's threat to beat her with a contemptuous, "Yeah, well, come on, badass."
When Jax decided to go nomad, Gemma tried to manipulate him into staying with SAMCRO, but fails.
When SAMCRO Got into a nursery to find Abel, Gemma soon started to pull a gun up to the head of one of their babies, Jax tried to stop her but failed. When Jax found Abel with another family, he was willing to him because he wanted him to have a better family. When Jax told Gemma, she smacked him in the face as she always does, and later blamed Kellan Ashby for it.
Gemma actually killed Tara by punching her three times, pushing her head down into a sink filled with water and stabbing her in the back of the head in a cowardly way.
Gemma and Juice conspire together and pin Tara's murder on the Chinese using Juice's knowledge of SAMCRO's beef with the Lin Triad. At Jax's housewarming party, Gemma singles out a Chinese partygoer after learning he has no family and nothing to lose, causing Jax to respond by torturing the man and murdering him in the same manner as Tara. Abel is the first person (other than Gemma and Juice) to find out about Tara's murder as he overhears her confession while she cries and cradles Thomas in her arms. In the episode "Suits of Woe", Jax finally learns the truth as Juice confesses everything to him, leaving him shocked and stunned at his mother's actions. Jax tells Nero and SAMCRO as Gemma flees to Oregon for her own safety.
Gemma visits her father in the nursing home and makes amends with him, apologizing for being so reckless growing up and telling him that he was a good father. Gemma sits in his house looking over childhood memories when Unser shows up, prepared to arrest her under Nero's orders for her own safety but Jax shows up. Unser refuses to leave Jax alone with Gemma, causing Jax to fatally shoot Unser in the chest. Gemma calmly accepts her fate and requests to go out into the garden she loved one last time. After some hesitation, Jax shoots Gemma in the back of the head, killing her.