Steven Moffat
On 8 May 2015, the BBC press office officially confirmed Harness would be writing a 2-part story titled "The Zygon Invasion" and "The Zygon Inversion" (the latter co-written with Steven Moffat) for the ninth series of "Doctor Who". The story sees the return of UNIT, Jemma Redgrave, Ingrid Oliver and the Zygons. He also co-wrote the seventh episode of the tenth series with Steven Moffat, titled "The Pyramid at the End of the World".