Diagoras

Mr. Diagoras was the man in charge of construction of the Empire State Building. He was a servant of the Cult of Skaro and ordered the construction to fit the demands of Dalek Caan, who served as the Cult's connection to the outside world.

Biography
Diagoras fought in World War I as a soldier and it was at that time that he decided to take care of himself. No matter what it would take, he wanted to run New York City.

The Cult thought Diagoras was the most Dalek-like human they had encountered, as he had rare ambition and thought like a Dalek. Dalek Sec viewed Diagoras as their best option for the Final Experiment, so Caan took him to meet their leader.

The Cult took hold of Diagoras and Sec planned to merge with him. Daleks Jast and Thay protested, but Sec convinced them that polluting the Daleks' purity was necessary. Sec fully opened his casing and Diagoras was pushed into his Dalek-mutant flesh, Sec completely encasing his body in his, and the casing was closed. When the Final Experiment was completed, the casing opened and Sec stepped out, transformed with Diagoras into the first human-Dalek.

It is unclear whether Diagoras was still living when he was merged with Sec or if his mind was aware of his surroundings.

What was left of Diagoras, merged with Sec, was exterminated by Dalek Thay. (DW: Daleks in Manhattan, Evolution of the Daleks)

Personality
Dalek Caan noted that Diagoras thought like a Dalek. Diagoras was an ambitious man and generally appeared to be cold towards others. He also had a short temper, frequently snapping at anyone who questioned his orders.

Despite his seemingly cold nature it is interesting to note that Dalek Sec gained human emotions after merging with Diagoras, which included mercy and compassion. This indicates that Diagoras may not have been as cold and aggressive as he appeared and might not have had as much in common with the Dalek's as Caan had thought.