Steela Gerrera was a human female from the planet Onderon, and an Onderonian by birth, who lived during the Clone Wars. As the leader of the Onderon rebels, a role she assumed from her brother Saw Gerrera, she engaged in combat. With the help of the Jedi, her group's actions resulted in the removal of Separatist control on Onderon, which was exerted through their representative, King Sanjay Rash, and the reinstatement of the kind King Ramsis Dendup. She and the Onderonian politician Lux Bonteri shared a romantic connection. Gerrera met her end in the final battle against the droid forces stationed on Onderon, and she was celebrated as a hero by her people.
When the Confederacy of Independent Systems seized control of Onderon, Steela Gerrera, along with her brother Saw and fellow insurgents, sought refuge in the planet's wilderness. It was there that she and the other insurgents established a resistance force. Following contact between her brother, former Separatist Senator Lux Bonteri, and the Jedi Council, she encountered the council's delegation, which included Jedi Master Obi-Wan Kenobi, Knight Anakin Skywalker, his Padawan Ahsoka Tano, and Clone Captain Rex.
Gerrera then escorted them to their hidden camp, where she, Bonteri, her brother, and the other insurgents underwent training. Initially, Gerrera was skeptical of the involvement of outsiders in Onderon's internal affairs. However, she understood that this intervention was necessary because of how Sanjay Rash had ousted Ramsis Dendup. During the training sessions, Gerrera demonstrated remarkable skill as a sharpshooter. After successfully eliminating a contingent of the droid army, Gerrera and the others devised a plan to infiltrate Iziz, the capital city, by disguising themselves as hunters and foragers. Subsequently, she and her companions dispersed to gather essential supplies, with the intention of reconvening later that night.
Gerrera recognized the importance of gaining the trust of the local populace. To achieve this, she orchestrated an assault on the power generators. Along with her brother and Bonteri, she neutralized a droid patrol, which in turn summoned an AAT. Together, they commandeered the tank and used it to destroy the generators. Following this successful operation, Gerrera was chosen as the leader of the resistance, much to her brother's disappointment. Steela then broadcasted a message to the people, denouncing Rash and the Separatist occupation forces. Upon learning that Rash intended to execute Dendup, Gerrera realized that they lacked the immediate resources for a rescue. She planned to intervene during the execution itself, but her brother was captured by General Kalani's guards. During the execution, Gerrera and her allies managed to halt the proceedings, only to find themselves surrounded by battle droids. However, her brother successfully persuaded Royal Militia General Akenathen Tandin and his troops to assist in their escape and liberate Onderon. Gerrera, her resistance, and the Royal Militia then retreated to the Highlands.
Steela, Ahsoka, and Lux arrived just in time to save the king from the droids. On the nearby battle field, Saw shot down the last of the enemy gunships, but the damaged unit careened out of control, right into the rebel camp. Steela was trapped on a collapsing rock on the edge of a cliffside, broken loose by the droid's impact, and while trying to jump to safety, she was caught hanging from the cliff. Lux rushed to save her, but nearly fell off himself. Ahsoka used the Force to float him to safety, but as she tried to do the same for Steela, the downed gunship fired a laser blast through Ahsoka's left shoulder, breaking her concentration and causing Steela to inadvertently fall to her death.
Following Steela's death, Saw became disillusioned with the Jedi. He carried a hologram projector of his sister to remind him of her. When Saw's militia was confronted by Clone Force 99 following the Proclamation of the New Order, Saw lamented, stating that the Empire would undermine all that was fought for, as well as all those who were lost, such as Steela, during the Clone Wars.
Saw later told the story of Steela's death to Jyn Erso during her childhood while she was under his care. When arguing with one of his allies, Idryssa Barruck, Saw said that Barruck reminded him of Steela, and said his comment was not entirely a compliment.
During an investigation on Geonosis, Saw managed to drop the projector of her but it was recovered by Ezra Bridger who asked if the woman in the hologram was Saw's sister, him saying that the image was all he had left of her.
During the Destruction of Jedha City, Saw called out to Steela in his last seconds of life after his Partisans' base on Jedha was destroyed by the Galactic Empire.