- "Those 631s are not the brightest lights on the ship."
- ―A B1 battle droid on the inferior capabilities of the 631 model
The 631 was a model of B1-series battle droid used by the Separatist Droid Army during the Clone Wars. Like other B1s, they were manufactured by Baktoid Combat Automata and Baktoid Armor Workshop and had masculine programming with black photoreceptors, bone-white plating, a comlink booster pack, and stood 1.93 meters in height. However, 631s were more clumsy and even less intelligent than other B1s, who regarded them as inferior.
In the year 22 BBY, 631 units were stationed on Skytop Station, a Separatist listening post located on the Ruusan moon. One 631 was tasked with carrying an item upstairs without dropping it. No sooner had the droid turned around than he immediately tripped and dropped the item.