Udilf

 was the leader of a town in eastern Europe sometime in the early 11th century.

Uldif and Mang had been business partners. Uldif had the ability to know what people needed, and Mang was a skilled craftsman. When the town needed a new leader, they chose Uldif. Mang disagreed with the decision, but treated Uldif with respect.

When a race of "creatures" began attacking nearby villages, Uldif prepared the town for battle. The townspeople made weapons and armour.

Uldif welcomed the Fifth Doctor and his companions when they arrived at the town. He didn't agree with the Doctor that the creatures could be reasoned with, but he allowed the Doctor and Adric to try. When they returned with the news that the "creatures" were merely humans of different appearance, he allowed the Doctor to contrive ways of scaring the invaders off.

The Doctor's plans failed to stop the invaders, however, and Uldif was one of several who died in the attack. He died outnumbered but with a sword in his hand. (PROSE: The Immortals)