Nemesis (TFA)

The Nemesis is the Decepticon command ship, originally under the command of Megatron.

Animated
The Nemesis was a Decepticon warship under the control of Megatron. It showed up on the outskirts of Autobot-controlled space almost immediately after the legendary All Spark was discovered by Optimus Prime and his crew of [[space bridge repair-bots. It attacked Prime's ship, the Ark, in an attempt to capture the All Spark.  Megatron went out to attack the Ark and seize the All Spark personally, unaware his lieutenant, Starscream, had planted a bomb on him.  When the bomb detonated, the Ark went out of control, plunging toward another space bridge portal.  The All Spark opened the space bridge and caused a shock wave after the Ark went through, slagging the Nemesis and Starscream inside, while the other Decepticons escaped.  For the next fifty solar cycles, Starscream piloted the remains the ship, searching for the All Spark to show the Decepticons he deserved to be their new leader.  When its systems detected an All Spark-like energy signature from a remote star system, he went to investigate.  En route, he monitored television transmissions that depicted Prime and his Autobots as the new superheroes of Detroit.

Its current location is unknown, as Starscream was not seen aboard it while within Earth's vicinity. The ship may have been on or near Earth when he monitored the TV transmissions, or it may not. It's possible Starscream has placed it somewhere on Earth, though it could also be in orbit or even on the Moon. It's also possible, though much less likely, that he left it somewhere much further away and traveled to Earth in an escape pod.