Doppelgänger

Doppelgängers were individuals who were identical to other individuals.

Coincidental doppelgängers

 * Abbot of Amboise, Robert Bellarmine and the First Doctor. (DW: The Massacre) (MA: The Empire of Glass)
 * Ramón Salamander and the Second Doctor. (DW: The Enemy of the World)
 * Strella and Romana I. (DW: The Androids of Tara)
 * Ann Talbot and Nyssa. (DW: Black Orchid, MA: The Sands of Time)
 * Peri and Queen Anne (but Queen Anne had a crooked nose). (BFA: The Church and the Crown)
 * William Pike and his great-grandson Darius Pike. (K9TV: The Cambridge Spy)
 * Barker and his great-grandson Thorne. (K9TV: The Cambridge Spy)
 * Gwyneth and Gwen Cooper. (DW: Journey's End)

The last case may have been a result of spatial genetic multiplicity.

Deliberate doppelgängers

 * The Daleks created a robot double of the First Doctor. (DW: The Chase)
 * The Chameleons adopted the appearance of several people including Polly. (DW:The Faceless Ones)
 * General Scobie came face-to-face with his Auton replacement. (DW: Spearhead from Space)
 * Bill Filer was duplicated by Axos. (DW: The Claws of Axos)
 * The Zygons impersonated several people including Harry Sullivan. (DW: Terror of the Zygons)
 * The Fourth Doctor, Sarah Jane Smith, Sergeant Benton, and Harry Sullivan were all duplicated as robots by the Kraals. (DW: The Android Invasion)
 * Prince Reynart's robot double was crowned king in his place. (DW: The Androids of Tara)
 * Cessair of Diplos created an image of the Doctor that caused Romana to fall over the edge of a cliff.(DW: The Stones of Blood)
 * Romana II chose to take on the appearance of Astra of Atrios when she regenerated. (DW: The Armageddon Factor and Destiny of the Daleks)
 * Meglos and the Fourth Doctor (DW: Meglos)
 * Omega and the Fifth Doctor. (DW: Arc of Infinity)
 * Kamelion took on the form of King John of England and momentarily, the Fifth Doctor, the Master and Tegan Jovanka. (DW: The King's Demons)
 * The Daleks created multiple duplicates, Stien amongst them. (DW: Resurrection of the Daleks)
 * Sharaz Jek created android doubles of Major Salateen, the Doctor and Peri. (DW: The Caves of Androzani)
 * A Kymbra Chimera took on the form of the Sixth Doctor and Peri Brown while in the Doctor's TARDIS. (DWM: Changes)
 * Dr. Who and the Seventh Doctor. (NA: Conundrum, Head Games)
 * A clone of the Sixth Doctor. (BFA: Project: Lazarus)
 * The Autons created a duplicate of Mickey Smith. (DW: Rose)
 * Martha Jones was cloned by the Sontarans. (DW: The Sontaran Stratagem)
 * Drake created a duplicate of K9. (K9TV: Jaws of Orthrus)
 * The Autons created a duplicate of Rory Williams. (DW: The Pandorica Opens/The Big Bang)
 * The Justice Department Vehicle known as the Teselecta took the form of Rasputin with green skin. In 1938 Berlin, it took the form of a janitor, a Nazi official, a Nazi soldier (both with and without a motorbike), Amy Pond, and River Song (DW: Let's Kill Hitler) and in 2011 Lake Silencio, it took on the form of the Eleventh Doctor. (DW: The Wedding of River Song)
 * The spirits of the 49th century took bodies on purpose so that they could be free once more. (JAL:  The Spirit Trap)

Other

 * The Third Doctor travelled to a parallel universe and encountered other versions of Alistair Gordon Lethbridge-Stewart, Liz Shaw, and John Benton. (DW: Inferno)
 * The Tenth Doctor travelled to a parallel universe and encountered other versions of Mickey Smith, Jackie Tyler, Pete Tyler, and the Cybermen. (DW: Rise of the Cybermen)
 * Zagreus and the Eighth Doctor (BFA: Neverland, Zagreus)
 * Townsend, Tepesh, and Winky were projections of the Seventh, Sixth, and Fifth Doctors (BFA: Zagreus)
 * The Tenth Doctor transferred his regeneration energy to his hand, and when Donna Noble touched it, she created a clone of the Doctor. (DW: Journey's End)