Tarn was a Proto-Time Lord clone of River Song.

Tarn was created on Demons Run by Madame Kovarian, along with six other clones. After escaping Demons Run with his fellow clones, he learned of Lake's ability to regenerate and regarded him as a spiritual leader. Due to Lake's religious teachings, Tarn believed regeneration was a constant rebirth. He went to Terminus Prime to commit suicide so he could continually be born again. By the time he met River, he had already died eight times. He was killed again by Kevin and then again by Dave. When he met River again he believed she was trying to stop him from fulfilling his religious path and wanted nothing to do with her. (AUDIO: The Lady in the Lake)

Behind the scenes[]

Like all of his siblings, Tarn's name is a reference to water, with his name coming from the word tarn, which is a mountain lake, pond or pool, formed in a cirque excavated by a glacier.