"The reign of biological lifeforms is coming to an end..."
Lore was a Soong-type android constructed by Doctor Noonian Soong and Juliana Soong at the Omicron Theta colony and activated on September 9, 2335. Built in Dr. Soong's own image, Lore was the fourth android they constructed and embodied the first successful example of a fully-functional positronic brain. An earlier model Soong-type android, B-4, also had a positronic brain, but of a less sophisticated type. Lore was extremely advanced and sentient, possessing superior strength, speed and intelligence when compared to a Human. Lore's emotional programming was also very advanced. However, he began displaying signs of emotional instability and malevolence, leading Lore to see himself as superior to Humans. Lore frightened the other colonists, who demanded that Soong deactivate him. Lore later claimed that they saw him as "too perfect", and were envious.
Eventually Soong capitulated, but not before Lore had secretly contacted the Crystalline Entity in a bid for revenge, offering it the planet's life to ensure his own survival. After deactivating and dismantling Lore, Soong set about constructing Lore's brother Data, an android without destabilizing emotions. Lore's positronic net differed from Data's in that it had a Type-"L" phase discriminator, compared to Data's Type-"R". (TNG: "Time's Arrow") Soong placed Lore's components into storage, intending to eventually correct Lore's behavioral problems. Lore later harbored resentment towards his creator for abandoning him. Yet, when he met his father again on Terlina III and learned that Soong was dying, he was sincerely upset and, for a brief moment, he displayed a genuine concern for his father. Nevertheless, Lore's malevolent streak soon prevailed.
Following Lore's communiques, the Crystalline Entity attacked Omicron Theta during 2336, and destroyed all life on the planet. Both Lore and Data were left behind, but Data was subsequently discovered in 2338 by the crew of the USS Tripoli. Lore remained in Soong's laboratory until 2364, when the USS Enterprise-D arrived at the planet. The ship's chief engineer, Lieutenant Commander Argyle, and chief medical officer, Dr. Beverly Crusher, were successful in reactivating the android. Lore immediately returned to his previous ways, deactivating Data, stealing his uniform, and masquerading as him. Lore summoned the Crystalline Entity once again, intending to feed the crew of the Enterprise-D to it. His treachery was discovered due to the differences between him and Data (such as his use of contractions), and he was transported into open space. (TNG: "Datalore", "Silicon Avatar")
Lore drifted in space for nearly two years until he was rescued by a passing Pakled ship. Lore subsequently responded to the homing signal intended by Soong to draw Data to Soong's new laboratory on Terlina III. After Soong had reactivated Lore, Lore expressed frustration at his father's 'dismissal' of him in favour of working on Data, but was apparently as close to upset as he could come when he learned that Soong was dying, protesting that his father seemed fine despite his obvious age. However, his grief for his father was overshadowed by his anger when he learned that Soong had summoned Data to him with the intention of giving Data an emotion chip that would allow him to feel Human emotions(as Data's emotionless "childhood" had given him a greater understanding of right and wrong), Lore resenting his father's 'favoritism' of Data despite Soong's protests that he had never designed a chip for Lore simply because he assumed that Lore had remained deactivated. Despite Soong's attempt to placate Lore, Lore nevertheless tricked Soong by posing as his brother and stealing the chip for himself. The chip caused Lore to become even more unstable and he killed Soong. (TNG: "Brothers")
In 2369, Lore discovered a group of Borg that had been disconnected from the Collective after integrating Hugh's sense of individuality into the hive. Lore styled himself their leader, gave his Borg individual names, coercing them into fanatical followers. He began cruel experiments on them, attempting to replace their organic brains with positronic components. Meanwhile, he somehow influenced their behavior, making their attacks more violent – they ceased to assimilate individuals, instead murdering them. Lore directed his Borg followers to launch attacks on targets in Federation space, in order to lure the Enterprise-D--and thus Data--in an elaborate attempt to use the emotion chip to manipulate Data to his side. Lore had modified the chip so that it could remotely instill anger and hatred in Data. Confused with his new emotions, and with his ethical subroutines deactivated, Data betrayed the crew of the Enterprise-D and joined Lore at his base. (TNG: "Descent")
While in Borg captivity, Geordi La Forge was able to instruct Captain Jean-Luc Picard as to modifying a Borg interlink transceiver in order to reset Data's ethical program with a kedion pulse, restoring his sense of right and wrong. Data would still experience negative emotions; however, he could at least choose whether or not to act upon them. Upon realizing Lore's malign nature, Data fired upon and deactivated Lore, whose last words were "I... love you... brother." Lore was subsequently dismantled--and the emotion chip, though damaged, was removed and returned to its rightful owner. (TNG: "Descent, Part II")
Lore was played by Brent Spiner in all of his four appearances. Ken Gildin, Brian Tomlinson, Dana Vitatoe and Guy Vardaman served as photo doubles for Spiner in these episodes while Brian J. Williams was the stunt double in the episodes "Datalore" and "Descent, Part II".
The Pakled costume worn by Spiner as Lore in "Brothers" was sold off on the It's A Wrap! sale and auction for US$2,155.00.  Other items which were sold off on eBay include the special effects thumb from "Brothers" , Dana Vitatoe's costume from "Brothers" , Spiner's and Williams' costume from "Descent" and "Descent, Part II"   and the utility jumpsuit from "Datalore". 
Lore was originally planned to be a female android to provide a love interest for Data. Her job would have been to go out and repair dangerous situations. It was Brent Spiner who suggested the old "evil twin" concept be used instead. (Star Trek: The Next Generation Companion 2nd ed., p. 46) The female android concept was later used in the third season episode "The Offspring".