Sunad was a 24th century Zalkonian warship commander.
In 2366, Sunad was engaged in genocide against all Zalkonians who displayed isoelectric bursts. These individuals were evolving into a higher lifeform. Sunad had destroyed a ship of escaped prisoners whom he believed to have eliminated.
Sunad intercepted the USS Enterprise-D in attempt to extradite the Zalkonian fugitive "John Doe". When the Enterprise-D crew refused to give him "Doe", Sunad used a beam of energy to paralyze the crew. "Doe" then saved the crew. He beamed Sunad aboard the Enterprise-D and tried to reason with him, but Sunad would not listen. (TNG: "Transfigurations")
Sunad was played by actor Charles Dennis.
His name was an inversion of TNG writer Richard Danus. (Star Trek Encyclopedia, 3rd ed., p. 482) He was named Setan in the first draft script.
The costume worn by Dennis as Sunad was sold off on the It's A Wrap! sale and auction on eBay. [1](X)