In "Trial of a Time Lord: The Ultimate Foe", the Master tells the Doctor:
"There is some evil in all of us, Doctor – even you. The Valeyard is an amalgamation of the darker sides of your nature, somewhere between your twelfth and final incarnation, and I may say you do not improve with age."
Because of the War Doctor, the "twelfth incarnation" of the Doctor would be #11 (Matt Smith). So it can't be the Eleventh Doctor himself, but a Doctor after him.
However, in the novelization, the Master says that the Valeyard is an incarnation of the Doctor "Somewhere between [his] twelfth and thirteenth regeneration." The twelfth regeneration was from #10 (David Tennant) to #11 (due to using up a regeneration to remain the same, resulting in the Metacrisis Doctor), and the thirteenth regeneration was from #11 to #12 (Peter Capaldi). So it would seem only Matt Smith's Doctor is between his twelfth and thirteenth regenerations, but as you remember, it can't be him.
However, there is someone who fits the bill: the Ganger Doctor from the episodes "The Rebel Flesh" and "The Almost People". He's between Matt Smith's incarnation and the Doctor's final incarnation. He's also between the Doctors 12th and 13th regenerations. Only issue is how he survived, since it appears that he died in "The Almost People". Perhaps, because he's a ganger of a Time Lord, he was able to somehow regenerate after being turned into liquid, but ended up changed after his liquid mixed with the monster ganger.
(I kinda wanted the Metacrisis Doctor to be the Valeyard, especially after seeing David Tennant as Killgrave in Jessica Jones, but the math doesn't work, so I guess it wasn't meant to be.)
"There is some evil in all of us, Doctor – even you. The Valeyard is an amalgamation of the darker sides of your nature, somewhere between your twelfth and final incarnation, and I may say you do not improve with age."
Because of the War Doctor, the "twelfth incarnation" of the Doctor would be #11 (Matt Smith). So it can't be the Eleventh Doctor himself, but a Doctor after him.
However, in the novelization, the Master says that the Valeyard is an incarnation of the Doctor "Somewhere between [his] twelfth and thirteenth regeneration." The twelfth regeneration was from #10 (David Tennant) to #11 (due to using up a regeneration to remain the same, resulting in the Metacrisis Doctor), and the thirteenth regeneration was from #11 to #12 (Peter Capaldi). So it would seem only Matt Smith's Doctor is between his twelfth and thirteenth regenerations, but as you remember, it can't be him.
However, there is someone who fits the bill: the Ganger Doctor from the episodes "The Rebel Flesh" and "The Almost People". He's between Matt Smith's incarnation and the Doctor's final incarnation. He's also between the Doctors 12th and 13th regenerations. Only issue is how he survived, since it appears that he died in "The Almost People". Perhaps, because he's a ganger of a Time Lord, he was able to somehow regenerate after being turned into liquid, but ended up changed after his liquid mixed with the monster ganger.
(I kinda wanted the Metacrisis Doctor to be the Valeyard, especially after seeing David Tennant as Killgrave in Jessica Jones, but the math doesn't work, so I guess it wasn't meant to be.)