Blood Blood was an essential fluid of many life forms , Gallifreyan s and human s included . Human blood , which was red , was divided into two types of blood cells , red and white , with red containing iron . ( TV : " Bad Wolf " ) Some people , like Chief Steward Weeks , didn ' t enjoy the sight of blood . ( AUDIO : " Storm Warning " ) Sleep dust contained , among other things , blood cells . ( TV : " Sleep No More " ) Significance . Food and drink . Some organisms consumed blood in order to survive , namely vampire s , ( TV : " State of Decay " ) Haemovore s ( TV : " The Curse of Fenric " ) and Plasmavore s . ( TV : " Smith and Jones " ) The Three Who Rule would only drink the blood of the living . However , they killed villagers and used tubing to store their blood in the fuel tanks of the " Hydrax " . This was then fed to the King Vampire . ( TV : " State of Decay " ) On their home planet , the Ogri subsisted on amino acids , but found that the blood of Earth life forms , including humans , would also suffice . This led to human sacrifices at Stonehedge . ( TV : " The Stones of Blood " ) Other species , such as Vortisaur s ( AUDIO : " Storm Warning " ) and Androgum s , ( TV : " The Two Doctors " ) did not subsist off of blood exclusively , but would consume it as part of a more varied diet . While stranded in four - dimensional space , the Eighth Doctor claimed that Vortisaurs could smell the space - time in his Time Lord blood . ( AUDIO : " Storm Warning " ) As Vastra herself implied , she would drink human blood as a refreshment , calling it " the colour of red wine " . ( TV : " The Snowmen " ) At least one Osiran , Sekhmet , enjoyed feasting on blood . ( AUDIO : " The Bride of Peladon " ) Practical use . The magic potion Lady Peinforte made to travel in time required human blood . ( TV : " Silver Nemesis " ) Some species , including the Sycorax , used a form of hypnosis known as blood control . ( TV : " The Christmas Invasion " ) Blood could be transferred to another by the process of blood transfusion . The Eighth Doctor once gave blood to his fourth incarnation via this process . ( PROSE : " The Eight Doctors " ) Mortimus used the blood of five species whose destinies the Time Lord s had affected in a ritual to summon Artemis , the Chronovore . ( PROSE : " No Future " ) Blood also formed an important part of some Faction Paradox rituals . Sometimes biodata would be extracted from the blood of a being to use in a Faction Rite or Ritual . ( PROSE : " Alien Bodies " ) Judoon scanner s checked blood to gather information on the unit ' s species . ( TV : " Smith and Jones " ) In 2011 , Jack Harkness ' s immortal blood was used by the Three Families to cause Miracle Day , by inserting it into both ends of the Blessing simultaneously . Later that year , the Miracle was stopped when Jack , now mortal because of Miracle Day , inserted his blood into one end of the Blessing at Shanghai , while Rex Matheson , who had a transfusion of Jack ' s mortal blood , inserted it into the other end in Buenos Aires . ( TV : " The Blood Line " ) As a failsafe , Sekhmet ' s trisilicate prison was blood lock ed . The lock required the blood of four royal women to properly release Sekhmet . ( AUDIO : " The Bride of Peladon " ) When trapped in 1941 and trying to send a message to her 21st century Torchwood Three team , Toshiko Sato cut her hand with a sharp edge of a can , and wrote on paper with her blood . ( TV : " Captain Jack Harkness " ) The Twelfth Doctor had a gizmo able to take a sample and examine outrigh a specimen of human blood . He administered such a test on Alan - a - Dale , a human from the 12th century , and made a prognosis of several diseases and about six months of life expectancy . ( TV : " Robot of Sherwood " ) Blood types . On at least Earth , blood was organised into different types . A - positive was the most common type , with one third of human ity in 2006 being A - positive . This was exploited by the Sycorax , who used a sample of A - positive blood in Guinevere One to hypnotise all A - positives via blood control . ( TV : " The Christmas Invasion " ) Charley Pollard ' s blood type was AB - negative . ( AUDIO : " Absolution " ) The First Doctor had TL - positive blood . ( PROSE : " A Big Hand for the Doctor " ) According to Dr Lomax , the Third Doctor ' s blood had a blood type unidentifiable as human blood , as shown by its platelet stickiness . ( TV : " Spearhead from Space " ) Colour . There were many variations in blood colour . Human ( TV : " Smith and Jones " ) , Time Lord ( TV : " The Two Doctors " , " Heaven Sent " , " Extremis " ) and Raxacoricofallapatorian ( PROSE : " The Monsters Inside " ) blood was red . Time Lord blood was a darker shade of red than human . ( TV : " The Christmas Invasion , Extremis " ) The 456 also had red blood . ( TV : " " ) The Ood had purple blood , ( TV : " Planet of the Ood " ) as did the Venusians . ( PROSE : " Venusian Lullaby " ) One pilot ' s species had pale blue blood . ( PROSE : " Joyride " ) Sontaran , Foamasi , Kaled / Kaled mutant , Ice Warrior and Meep blood was green . ( TV : " The Two Doctors " , " The Leisure Hive " , " Revelation of the Daleks " , " The Last Sontaran " , COMIC : " The Star Beast , AUDIO : The Prisoner Of Peladon " ) The Waro had yellow - green blood . ( PROSE : " The Devil Goblins from Neptune " ) Mayflies and Judoon had yellow blood . ( TV : " Reset " , " Prisoner of the Judoon " ) Nostrovite s had black blood . ( TV : " Something Borrowed " ) Silent blood was white . ( TV : " Day of the Moon " )