The U.S.S. Pollux was a Federation starship in service to Starfleet in 2409. In that year, she fought alongside the U.S.S. Byzantium and U.S.S. Sri Lanka against the Crystalline Entity, which was attacking a Federation colony in the Teneebia Sector.
The Pollux took point against the Entity, leading the strike team into firing range. Though the vessel did some damage to the Entity, she was eventually lost with all hands after a shard from the Entity followed the starship and sliced her in half. The Sri Lanka was destroyed shortly after; the Byzantium was the only vessel to escape the carnage.