Q-Ships are massive spaceships used by Thanos and the Black Order. These ring-shaped vessels were stored inside the even larger Sanctuary II, and Thanos deployed them during his invasions of Zen-Whoberi and Earth.
In 2014, the Black Order invaded an unnamed planet. Once their task was complete, Gamora and Nebula returned to their Q-Ship where they discussed Thanos finally putting his plan into motion. It was then that Thanos teleported aboard, informing his daughters that Ronan the Accuser had located the Power Stone and that he was assigning them to the Dark Aster as his wardens.
Concurrently, Corvus Glaive and Proxima Midnight used a second Q-Ship to travel to Edinburgh to claim the Mind Stone from Vision. The two managed to corner the android and Scarlet Witch in a train station before being ambushed by Steve Rogers, Black Widow and Falcon, which resulted with Glaive being gravely wounded. Knowing that the odds are against them, Midnight beamed herself and Glaive back up to their Q-Ship and fled from the area.
Five years after the Snap, the surviving Avengers planned to reverse it by stealing past versions of the Infinity Stones. Along with War Machine, Nebula travelled back to Morag on 2014 to acquire the Power Stone. When they arrived however, Nebula's implants began syncing with those of her past self allowing the past Thanos, who'd just boarded Nebula's Q-Ship to learn of what was happening. Ordering Nebula brought to the Sanctuary II, the Q-Ship docked with the larger craft where Nebula was brought to the lab.
Once the time travel was discovered, Thanos had his Nebula pose as her future self and travel to 2023 so she could summon him and his army whereupon he would claim the Infinity Stones and remake the universe. When Captain Marvel crashed into the Sanctuary II, the docked Q-Ships fell from the larger craft, chunks of them crashing onto the ground. Their remains were later disintegrated when Iron Man used the Infinity Stones to disintegrate Thanos and his forces.
- The meaning behind the name "Q-Ship", first revealed by Entertainment Weekly, has not yet been clarified; the ship was never referred to by that name in Avengers: Infinity War. However, the side view of the ship does visually resemble the letter "Q", suggesting that "Q-Ship" is a colloquialism for the vehicle.