8557 was a masculine-programmed B1-Series battle droid sentry assigned to a Trade Federation C-9979 landing craft. 8557, like all B1 battle droids, had black sensors. 8557 carried a E-5 blaster rifle. In 32 BBY, the Jedi Padawan Obi-Wan Kenobi sneaked aboard 8557's landing craft and sabotaged the atmospheric turbine engines to force the ship to land on Naboo. Another battle droid ordered 8557 to investigate the malfunction in the Turbine Control room.
8557 encountered Kenobi, who cut down the droid sentry using his lightsaber before proceeding further into the ship.
8557 appears in the Stowaway mission in the 2001 video game Star Wars: Obi-Wan after the player, in the guise of Kenobi, disables the engines. It is not necessary to destroy 8557, but this article assumes the player cuts down every battle droid. Instead of using the lightsaber, players may use a Force push to dispatch 8557. The droid was mentioned in the strategy guide, which tells players to go through the door 8557 opened.