Allopta was a Time Lord during the War in Heaven.
He was second-in-command for Xenaria's expedition to break the time loop surrounding Planet 5 about 12 million BC, so the Fendahl could be released and used against the Enemy. Like all members of the expedition, he had been changed into a Elder Thing as camouflage during the time period. He was highly questioning of Xenaria, almost to a treacherous level.
One and Two killed him and discarded his corpse into a gap in space-time, and then scanned his brain to learn more about what was happening. When they discovered he was a transformed Time Lord on a deep-cover mission, they each transformed into a copy of Allopta to infiltrate and learn more. (PROSE: The Taking of Planet 5)