I'm pretty certain that there has never been a mention in the series about a brother.
There have been mentions of the Doctor's family in that he has said he had to leave his family.
The End of Time implied that the woman that appeared and talked to Wilf was the Doctor's mother - although this is not stated explicitly.
I think Joe (in the comment) is right in that the implication is that the reference to "brother" was a reference to the Master.
scifi.stackexchange.com/users/1779/Lekarz Kto
Lots, if you know where to look, er, listen.
The Doctor's brother, Irving Braxiatel has quite a storied history IF you have listened to any of the audio products/broadcasts of the Dr Who Series.
Irving Braxiatel, or simply Braxiatel, was a Time Lord and the older brother of the Doctor.
He maintained the Braxiatel Collection .
At one time he held the office of Lord Cardinal in the High Council on Gallifrey.
He also briefly served as Lord Chancellor and Lord President of Gallifrey.
He was an associate of Bernice Summerfield .
Irving Braxiatel appeared in " The Inquiry " as Cardinal Braxiatel, produced by Big Finish Productions in 2004 and is played by Miles Richardson.
Some of these stories appear to take place in an alternative timeline called The Axis .
It is mentioned that at least in one alternative universe the Doctor may have had to kill his brother during a time when the Doctor was "The Burner", a temporal assassin for the Gallifreyan Council.
This could explain the Doctor's cryptic "not anymore statement".
Irving Braxiatel has also appeared in a number of novels as well.
He appears in The Empire of Glass , Tears of the Oracle and Dragon's Wrath to name just a few.
Irving Braxiatel does not appear to have made any onscreen appearances since the reboot of Doctors Nine through Twelve.
The Empire of Glass is a Virgin Missing Adventures original novel written by Andy Lane based on the long-running British science fiction television series Doctor Who.
It features the First Doctor, Steven Taylor, Vicki and Irving Braxiatel.
Tears of the Oracle : The shattered world of Dellah, once a thriving place of learning, has only one aspect of the university left.
This is under siege by religious fanatics.
Bernice Summerfield has to deal with this, a mad collector (Irving Braxiatel), her ex-husband and an Oracle that could lead to priceless information.
You can partake of the Doctor's brother Irving Braxiatel's complicated history at the Tardis Data Core where they track his appearances both in print and in audio.
You can also reference Big Finish Productions for other Dr. Who audio appearances.
scifi.stackexchange.com/users/2765/Thaddeus Howze
Thus far, there has been no explicit mention of a brother.
The only information we have on any immediate family of the Doctor is: Susan, his granddaughter, who appears regularly in the first ten serials or so (season one and start of season two).
A great-grandson by Susan, who appears only in some Eighth Doctor audio episodes
His mother, who appears (not acknowledged on-screen, but has since been confirmed) in the Tenth Doctor's final season finale.
Jenny, his cloned offspring, whom he has acknowledged as his daughter.[1]
Presumably he has at least one natural son/daughter, Susan's parent, but we are never told which.
Of course, if you buy the New Adventures novels, then Time Lords aren't born, they're "loomed" in batches of 40-50, all of which are called "cousins", but its usually best to just pretend that stuff never happened.
[1]:
As @Mr.
Lister correctly points out, Jenny is not strictly a "clone" of the Doctor; she was produced by some unspecified replication process based on his DNA, but obviously including some genetic variations.
She appeared physiologically to be Gallifreyan, so it's not clear where the alterations to her DNA came from.
Calling her a "daughter" is probably the closest term we can come in English.
scifi.stackexchange.com/users/2816/KutuluMike
Given that the Doctor may be a clone, via Looming, of The Other (as hinted in the book Lungbarrow) it's conceivable that he had a brother that way.
scifi.stackexchange.com/users/424/David Roberts
The Doctor's Brother might be this guy: http://en.wikipedia.org/wiki/Irving_Braxiatel
scifi.stackexchange.com/users/12312/Some Girl
While it has never been officially stated, Dr
Who scripts were written where it was reveal
The Doctor and The Master are half brothers.
Paul McGann read one as part of his audition for his role as the 8th Doctor.
scifi.stackexchange.com/users/119646/user119646
http://tardis.wikia.com/wiki/Irving_Braxiatel This link states that Braxiatel IS the Doctor's older brother.
scifi.stackexchange.com/users/16728/Brett
I remember long ago in a store looking at a Dr. Who novel or more likely a serial novelization, with a scene set in an alien underground city I think, where the Doctor and the Master were said to be brothers.
For along time I thought that was canon in the TV series.
If my memory is correct the Doctor and the Master were brothers in at least some part of Dr. Who literature.
scifi.stackexchange.com/users/75807/M.A. Golding
In the 10th Doctor episode  Smith and Jones  when Martha asks the Doctor if he has a brother, he says   No, not any more.    It seems like if there had never been any mention of a brother, and no plans to introduce (a history of) one, a simple "no" would have worked for the purposes of this episode.   Has there been mention of a brother in any other episode or any of the novels?
Is anything known about the Doctor's brother?
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scifi.stackexchange.com/questions/3815
scifi.stackexchange.com/users/108/Tony Meyer
The Doctor's brother, Irving Braxiatel has quite a storied history. It is mentioned that at least in one alternative universe, the Doctor may have had to kill his brother during a time when the Doctor was "The Burner", a temporal assassin for the Gallifreyan Council. The Doctor and the Master were said to be brothers in some part of Dr. Who literature. There do not appear to be any canon references to a brother in Dr Who. However, there are some suggestions that either Irving Braxiatel or the Master may be the Dr's brother.
It would appear there has been no explicit mention of a brother in the Dr Who series. There are references to a brother in other Dr Who sources. One possibility is  Irving Braxiatel, another is the Master. However, it is not clear if these references are canon.