Xandar is the home world of the Xandarians and home to many other species as the capital of the Nova Empire with a population of 12 billion. It was located in the Andromeda Galaxy. Xandar orbited around three suns. The planet was decimated by Thanos in order to obtain the Power Stone.
The Kree of Hala sought to attack Xandar during their war with its people. In 2014, a peace agreement was reached with the Kree Empire.
After obtaining the Orb on Morag, Star-Lord brought it to the Broker on Xandar and attempted to sell the Orb to him. The Broker questioned Star-Lord and in the process learned that the Orb was also also sought by Ronan the Accuser.
Fearing for his life if he acquired the Orb, the Broker refused to take the Orb and evicted Star-Lord from his shop. Gamora followed Quill to Xandar and ambushed him as he exited the store.
However, her planned attack was thrown off when the criminal duo of Rocket Raccoon and Groot arrived, instead seeking Quill who had a high bounty on his head from Yondu Udonta. In the confusion, Quill fled. Gamora and the two thugs raced after Quill, causing quite an uproar. Eventually, Gamora pinned Quill, but the Nova Corps quickly intervened and arrested the four for civil disruption.
Ronan the Accuser and his minions attempted to destroy Xandar using the power of the Orb. However, with the combined effort by the Nova Corps, the Ravagers and the Guardians of the Galaxy, his ship, the Dark Aster, was destroyed, and Ronan was killed.
Two months later, Xandar was one of the planets nearly assimilated by Ego, but the plan was stopped by the Guardians of the Galaxy.
Four years after Ronan the Accuser's attack, Thanos launched a brutal campaign to gather the Infinity Stones. The Orb was his first target, and he arrived in Xandar by force, annihilating the Nova Corps and Nova Empire to collect the Power Stone and then devastated half of the planet's population as part of his quest to balance the universe.