The Doctor has had 29 different companions since the program's launch in 1963. There are also many other characters who may or may not be classed as 'full-time' companions.
The Companions of Doctor Who was created in 1986.
They have all had multiple companions, apart from the eighth Doctor in the Doctor Who movie.
The way they are numbered in the show (not counting the War Doctor), Peter Capaldi is the twelfth. If you insert the War Doctor (John Hurt), then Matt Smith was the twelfth.
Sylvester McCoy, the Seventh Doctor, and David Tennant, the Tenth Doctor, are the only Scottish actors to have "officially" played the Doctor, though many companions and side-characters have been Scottish. UPDATE: As of 2014, Peter Capaldi has taken on the role of the Twelfth Doctor becoming the third Scottish actor to "officially" play the Doctor.
The Sixth Doctor's companions were Peri Brown, who traveled with him the longest, and Mel Bush.
In the revived series (2005 to the current series), two companions have fallen in love with the Doctor. The first is Rose Tyler (she proclaims her love for him at the end of SE2EP13: Doomsday) and the second is Martha Jones.
the most popular doctor who companions are Amelia Pond, Clara Oswald, and Rose Tyler
Who is the 12th Doctor of Doctor Who? The Answer you seek is Actor Peter Capaldi.
You can find a list in the Wikipedia article "Companion (Doctor Who)". Decide for yourself which ones you want to include - some were with The Doctor only briefly.
The Doctor has had many companions over the years in the TV show "Doctor Who." Some of the most notable companions include Rose Tyler, Martha Jones, Donna Noble, Amy Pond, and Clara Oswald. Each companion brings a unique dynamic to the Doctor's journey through time and space.
Eventually yes, he will regenerate into the twelfth Doctor.