Lurtz was the first leader of the Uruk-hai Scouts created specifically for Peter Jackson's movie The Lord of the Rings: The Fellowship of the Ring.

Lurtz was the first of Saruman's Uruk-hai to be bred, choking the first Orc he sees to death within seconds of his birth. Attempting to
intervene, other Orcs move towards the newly born Uruk-hai warrior, but Saruman halts their advance, intrigued by the malice and violence present in the Uruk's blood, leaving the unfortunate Orc to its fate. He became Saruman's second-in-command, and led the first battalion of Uruk-hai into battle against the Fellowship of the Ring at Amon Hen. Lurtz was born from the first batch of Uruk-hai in Isengard's pits (possibly even the first ever as an experiment), and so was far more developed, smarter and stronger than the later troops which were bred more quickly, presumably so Saruman could amass an army as fast as possible. Given that he gave orders to the other Uruk-Hai Scouts at the Amon Hen and given that he was given private audience with Saruman, he could presumably be called the strongest, smartest and most loyal of all of Saruman's Uruk-hai warriors.

Credit: lotr.wikia.com/wiki/Lurtz