The Marek family was a human family known to contain at least three Force-sensitive members beginning with Jedi Knight Kento Marek, and his wife, Mallie Marek, also of the Jedi Order. The family produced Galen Marek who became the Secret Apprentice of Darth Vader.
Kento met Mallie during the Clone Wars, and—going against the Jedi Code's restrictions against attachments and emotional bonds—the two fell in love. They secretly married and, following Mallie's pregnancy with Galen, quietly left the Jedi Order.
After exiling themselves and traveling from system to system while raising their son, the family became exiles in earnest at the issuance of Order 66. Reaching Kashyyyk, the family was welcomed by the native Wookiees and made themselves a more permanent home on the forest world.
The Marek family lived on Kashyyyk for more than a year. There they would remain even after Mallie was killed by Trandoshan slavers and mercenaries while protecting a group of Wookiees. In 18 BBY, Darth Vader arrived on Kashyyyk to continue his work in the Great Jedi Purge and slew Kento.
Galen was taken by the Dark Lord, codenamed Starkiller, and trained to be Vader's secret apprentice, his former identity and legacy forgotten. Galen later turned to the Light side of the Force and he was able to recall pieces of his forgotten life on Kashyyyk. However, the last member of the Marek family sacrificed himself for the fledgling Republic, fighting Palpatine and Vader on the—then unfinished—Death Star.