Mara Jade is a human female, introduced by Timothy Zahn in Heir to the Empire (Bantam Spectra, 1991). She was raised as the Emperor's Hand: a covert operative answering to Palpatine personally, outside the Imperial command structure, whose existence most of the Empire never knew about. Her homeworld has never been established, and this site is not going to invent one.
The last command
Her entire arc turns on an order she could not obey. At the moment of his death on the second Death Star, Palpatine's final instruction to her was to kill Luke Skywalker, and she spent five years unable to complete it and unable to let it go. The Thrawn trilogy introduces her as an enemy, keeps her an enemy for most of two books, and never lets the reconciliation feel cheap.
Her own career
What is easy to forget, given how she is usually described, is how much of the Legends shelf she carries in her own right — running Talon Karrde's smuggling organisation, then trading, then the New Jedi Order. Zahn's Survivor's Quest and his later novels treat her as a professional with a business, not a love interest with a lightsaber.
Legends only
Mara Jade does not exist in current canon. She has never appeared in a post-2014 novel, comic, film or series, and the position she occupied — Emperor's Hand — has been reworked into different characters entirely. She is the single most frequently cited example when readers argue about what the 2014 reset cost.
Reading note
Start with Heir to the Empire and read the trilogy straight through. Then, if you want the rest of the life, the Hand of Thrawn duology is where she and Luke are finally written as equals rather than as an unresolved argument.
