Star Trek: 25 Greatest Next Generation Episodes
15. Datalore
One of the stronger outings of season one introduced us to Data's evil twin brother, Lore. Yes, the early episodes were cheesy enough to introduce an evil twin.
When the Enterprise visits Data's home world Omicron Theta while on detached assignment, they discover the long lost Dr. Noonien Soong's laboratory. Soong disappeared from Earth years before and apparently came to Omicron Theta to start over by engineering Lore, a perfectly human android with emotions, and Data, a less human prototype.
The farmlands of Omicron Theta are laid waste by some external force, the Crystalline Entity, killing all the colonists save Dr. Soong and his creations, including Lore who lured the entity to the colony out of spite for the colonists' intimidation by him. He then incapacitates and poses as Data on the bridge, but not before luring said entity towards the Enterprise.