Max Capricorn

Max Capricorn owned the spaceship known as the Titanic.

Capricorn was a cyborg; only his head was organic. After having spent a hundred seventy-six years working for his company, only to be kicked out by his own board, he sabotaged Titanic's voyage so he could get revenge on his company for discrimination of his cyborg status. He used the Heavenly Host to damage the Titanic and kill the crew, leaving no witnesses. He planned to turn the Titanic into a giant bomb heading for Earth. When the board members of his company were accused of mass murder, they would be removed, after which he would retire to Penhaxico II.

His plan was foiled by Astrid Peth, who used a forklift to lift his entire cybernetic casing and throw him over the side of one of the Titanic's platforms. During the struggle, one of the Host cut the brakes of the forklift with its razor-sharp halo. Max and Astrid tumbled into the flaming engines far below. (TV: Voyage of the Damned)

Max's trademark was a gold tooth that flashed — both on camera and in person — when he introduced himself. This amazed the Tenth Doctor, who remarked, "It really does that?"

Alternate timeline
In an alternate timeline, his plan had successfully worked but had only destroyed London instead of the whole world.(TV: Turn Left)

Behind the scenes

 * Originally it was intended that Max Capricorn should have two milky-white eyes, but George Costigan could not see with both "cataract-lenses". Therefore, one was taken out, and the character was rendered with only one "bad" eye. (PCOM: Voyage of the Damned)
 * Iconic American actor was offered the role of Max (after being considered for the part of Mr Copper), and expressed interest, but the idea fell through, and Costigan was signed. (REF: The Writer's Tale)

The Visual Dictionary
The non-narrative source Doctor Who: The Visual Dictionary gave further information about Max Capricorn: His protective casing held an oxygen field, a device that allowed him to control the Titanic's engines, and a life-support system, which was secretly built on Sto.