Dors Venabili was one of the four friendly characters Hari Seldon came across when engaged in The Flight - the escape from the Emperor Cleon and supposedly the escape from Prime Minister Demerzel during the early days of psychohistory. She is an ancient robot, and was initially tasked by Hummin to protect Seldon from any and all dangers. He also became the wife of Seldon, and together they raised Raych, a boy they adopted from the Dahl sector of Trantor . When the reader initially meets her in Prelude to Foundation, she is a history professor at Streeling University .
Dors Venabili was a history professor at Streeling University when the reader first encounters her. She is assigned by Chetter Hummin to be Hari Seldon's protector. From the very beginning, she displays great gusto in the performance of her duty. Soon, during Seldon's Flight, she shows her amazing capabilities - on Mycogen, she contacts R. Daneel Olivaw in a mysterious manner, and on Dahl, she almost singlehandedly takes down a gang of ten men who were about to assault Hari Seldon. She does this using knives, despite the fact that she had had no prior training in their use. Eventually she gains the popular nickname of "Tiger Woman" during the Joranumite Conspiracy, during which she again shows her shrewdness and abilities.
This, and other cirumstances, finally convince Hari Seldon that Dors Vanabili is a robot, just like R. Daneel Olivaw. Despite coming to this conclusion (after initially learning about robots from the sacred text of Mycogen), Hari Seldon falls in love with Dors, and the latter, reciprocating his feelings in a mysterious way, accepts to become his wife.
Dors Venabili's feedback and historical expertise during the Flight was not only necessary to save Seldon many times, but was also responsible for many of the ideas Hari Seldon had that contributed to the early development of psychohistory.
The two also adopt Raych Seldon as their adoptive son. Not much is said of Dors Venabili's actions during the First Ministership of Hari Seldon, except that she continued developing her own studies in history, which helped develop psychohistory even further. However, near the end of this 10-year period, she is unable to protect Hari Seldon from an attempt at his life, carried out by remnants of the Joranumite Conspiracy who had their son, Raych Seldon, under mental control. Instead, the Seldons are saved thaks to the actions of Manella Dubanqua, an under-cover Imperial agent. This leaves Dors feeling inadequate, and she never forgives herself for her mishap. She also never shows any liking toward Manella Dubanqua, despite the fact that the latter soon becomes Raych Seldon's wife.
Prior to Hari Seldon's 60 birthday party (in Forward the Foundation), Dors begins suspecting a plot aimed to end Seldon's life. The only basis for her assumption is a "dream" young Wanda Seldon had while in Hari Seldon's office. The dream turns out to be an actual conversation between two people, one of them talking about "lemonade death." This ends up being a reference to Tamwile Elar, a young and promising mathematician who is secretly working with the junta that has been ruling Trantor since the death of Emperor Cleon I. When Dors confronts Elar, the latter activates a highly-tuned electromagnetic machine used to inscribe equations on the Prime Radiant. While the magnatic waves do no damage to humans, Dors, being a robot, is affected by them. She kills Elar, who unfortunately is able to turn the magnetic machine on full power. Dors stumbled to Hari Seldon's office, explains what has happened, then dies in his arms.