TX-21 was a masculine T-series tactical droid that served under Geonosian Archduke Poggle the Lesser in his droid foundry on Geonosis. Around 22 BBY, during the Clone Wars, the droid was stationed within the foundry during a battle on the planet of Geonosis. Outside the foundry, the Republic force was planning on destroying the foundry. TX-21 revealed to Poggle that the foundry had ten garrisons of new battle droids ready to be deployed. The Geonosian structure also housed new Confederate super tanks, a ray shielded tank capable of withstanding enemy fire, which were released on the attacking Republic forces outside the foundry. Soon, however, Poggle and the droid were alerted by a Geonosian that intruders had breached the foundry. The droid and Poggle confronted the intruders—Jedi Padawan