Age

Age was the length of time that a person lived or a thing existed, or had been alive. Different species could live out lifespans of various lengths, and reach different ages.

While the Fifth Doctor claimed to see the person, and not their age, instantly recognising an aged Piero, (AUDIO: Fallen Angels) the War Doctor took longer to recognise an older Rejoice, even with prompting. (AUDIO: The Thousand Worlds)

Gallifreyans
Romana stated that she was "nearly one hundred and forty" when she first met the Doctor. (TV: The Ribos Operation) A while after she regenerated, she stated she was one hundred and twenty-six. (TV: City of Death) She was one hundred and fifty by the time the Doctor was on Argolis. (TV: The Leisure Hive) Romana III, a later incarnation of Romana, was "thousands of years" older than her second self. (AUDIO: Renaissance)

Hours after his regeneration, the Seventh Doctor unlocked a door in 's laboratory with the numerical code "953", saying it was both his age and the Rani's. (TV: Time and the Rani)

The Doctor's age
The Doctor's age was widely inconsistent. The First Doctor was said to be 450 years old when he regenerated into the Second Doctor. (PROSE: Iceberg) The Seventh Doctor claimed to be 953 years old soon after regenerating, the same age as the Rani, (TV: Time and the Rani) yet by the time of his war incarnation, he claimed to be 400 years younger than his eleventh incarnation, who said he was "1200 and something". (TV: The Day of the Doctor) The Ninth Doctor claimed to be 900. (TV: Aliens of London) The Tenth Doctor claimed that he was 903, 904 and then 906. (TV: Voyage of the Damned, The Day of the Doctor, The End of Time) The Eleventh Doctor claimed that he was 907 a few days after regenerating, then 909, 1103 and then 1200. (TV: Flesh and Stone, The Impossible Astronaut, The Wedding of River Song, A Town Called Mercy) The Twelfth Doctor claimed to be around 2000 on numerous occasions, (TV: Deep Breath, Smile, Extremis) and roughly 1500 years older than he had been at the end of his first life. (TV: Twice Upon a Time)

Through their Time Lord ability to regenerate, the Doctor's true age was not reflected in their physical appearance. (TV: Last of the Time Lords)

Humans
Born in 1721, Jeanne-Antoinette Poisson recalled that she was seven years old when she first met the Tenth Doctor in 1727. At the age of 37, she was targeted by Clockwork Droids from the 51st century who believed that they needed her brain to repair their ship, the 37 year old SS Madame de Pompadour. In 1764, she died of an illness at the age of 43, which Louis XV commented was "too young". (TV: The Girl in the Fireplace)

Mrs Peace died at the age of 86 in 1869. (TV: The Unquiet Dead)

Having been born in 1894, Tommy Brockless was 24 years old in 1918, when he was cyrogenically frozen by Torchwood Three. 90 years later, Ianto Jones refered to him as "sort of" 24, acknowledging that he was now technically 114 years old. It was on this day that Tommy was returned to his own time, where he was executed soon after. (TV: To the Last Man)

As recalled by Elton Pope, he was "three or four" years old on the night of his mother's death. (TV: Love & Monsters)

Rose Tyler was six months old when her father Pete Tyler died in 1987. (TV: Father's Day, Rise of the Cybermen) She was said to be have been 19 on a poster when she left Earth with the Ninth Doctor and didn't return for a whole year. (TV: Aliens of London) Arriving in the year 2012, Rose noted that she would be 26 by this time. (TV: Dalek)

Jackie Tyler celebrated her 40th birthday in February 2007. (TV: Rise of the Cybermen) Later that year, she insisted that she was 40 when the Tenth Doctor, attempting to pass her off as Rose to Yvonne Hartman, claimed that she had aged 57 years as a result of looking into the time vortex. (TV: Army of Ghosts)

Lisa Hallett gave her age as 26 when asked by Doctor Tanizaki. At the time, her last memory was experiencing the Battle of Canary Wharf. (TV: Cyberwoman)

Though he was in fact artifically created by the Bane only months prior, (TV: Invasion of the Bane) Luke Smith appeared to be 14 years old when he entered Park Vale Comprehensive School in 2008, with Glune Fex Fize Sharlaveer-Slam Slitheen identifying him by this age. (TV: Revenge of the Slitheen) The following year, Sarah Jane Smith, Luke's adoptive mother, told the Tenth Doctor and other members of the Children of Time that her son was "only 14". (TV: Journey's End)

Richard Lazarus was 76 years old in 2008, when he used his hypersonic soundwave manipulator to reverse his physical age. He died that same night. (TV: The Lazarus Experiment)

Owen Harper died for the first time at only 27 years old. (TV: Dead Man Walking)

According to Rose Tyler, Chloe Webber was 12 years old at the time of the 2012 Olympics. (TV: Fear Her)

As determined by Strax during a medical examination, Clara Oswald was 27 years old following the Eleventh Doctor's regeneration. (TV: Deep Breath)

According to the Twelfth Doctor's sonic sunglasses, Nardole was 237 during the Monks' invasion of Earth in 2017. (TV: The Pyramid at the End of the World) As recalled by his glass avatar, he ultimately died at the age of 728. (PROSE: Twice Upon a Time)

Also during the Monk invasion, the sonic sunglasses registered Bill Potts as age 26, Xiaolian as 41, Don Brabbit as 59, Ilya Svyatoslavovich as 70 and the Commander as 63. (TV: The Pyramid at the End of the World)

As noted by the Tenth Doctor, Mia Bennett was "only" 27 years old on 21 November, 2059, the day she originally died before the Doctor changed history and saved her. (TV: The Waters of Mars)

At Kerb!am, Graham O'Brien gave his age as 310. (TV: Kerblam!)

As noted by Ida Scott, Scooti Manista was 20 years old when she was murdered by the Beast in 43K2.1. (TV: The Impossible Planet)

Attending Earth Death in the year 5,000,000,000, the Lady Cassandra O'Brien.Δ17 claimed herself to not look a day over two thousand. (TV: The End of the World)

Others
Blon Fel-Fotch Passameer-Day Slitheen was made to carry out her first kill at 13. (TV: Boom Town)

Korst Gogg Thek Lutiven-Day Slitheen was 12 when his father was killed. (TV: Revenge of the Slitheen)

The sonic sunglasses were unable to detect the ages of the Monks. (TV: The Pyramid at the End of the World)

Returning to the Ood Sphere in 4226, the Tenth Doctor asked Ood Sigma, who he had first met one hundred years earlier, how old he was. He did not receive an answer. (TV: The End of Time)

Strax was "nearly twelve", a "good life" for a Sontaran, when he fought in the Battle of Demons Run. (TV: A Good Man Goes to War)

At the time of his death, Brak was the longest-lived Sontaran in history, having lived over eighty years. (AUDIO: Old Soldiers)

According to legend, the Face of Boe was billions of years old by the time of his death in the year 5,000,000,053. (TV: Gridlock) Indeed, he was certainly alive as early as the year 200,000. (TV: The Long Game)

Reversing age
Seeking to escape the Last Great Time War, travelled to the far future where he used a Chameleon Arch to transform into a human baby which was left on the Silver Devastation. (AUDIO: The Heavenly Paradigm, TV: Utopia)

Looking into the heart of the TARDIS, Blon Fel-Fotch Passameer-Day Slitheen was regressed to an egg, which the Ninth Doctor took to Raxacoricofallapatorian to give her a second chance at life. (TV: Boom Town)

Through his invention of a hypersonic soundwave manipulator, 76 year old Richard Lazarus reversed his physical age, but the process resulted in dormant genes awakening and transforming him into a monster. (TV: The Lazarus Experiment)

Suspending age
In Pete's World, John Lumic invented the Cybermen, created through the conversion of humans to a metal "body that [would] never age or die". (TV: Rise of the Cybermen)

Having been preserved as a face in a pavement slab by the Tenth Doctor, Ursula Blake noted that she would never age. (TV: Love & Monsters)

After being brought back to life in an undead state with the resurrection gauntlet, Owen Harper stopped ageing. (TV: Dead Man Walking)

Accelerating age
Through use of technology from the Hypersonic soundwave manipulator incorporated into his laser screwdriver alongside a sample of the Tenth Doctor's biological code from his severed hand, accelerated his physical age by "a hundred years". (TV: The Sound of Drums) A year later, the Master further aged the Doctor. Regeneration capacity suspended and his true age of 900 brought to the surface, the Doctor was reduced him to a small and wizened creature. (TV: Last of the Time Lords)

Martha Jones' physical age was accelerated to her 80s when she was attacked by a resurrection gauntlet. The process was reversed when Duroc was defeated by Owen Harper. (TV: Dead Man Walking)

Invalid sources
According to the Metaltron's memory files seen in NOTVALID: The Last Dalek, a video game based on TV: Dalek, Henry van Statten was 40, Polkowski was 30, Diana Goddard was 25, Simmons was 30, and Adam Mitchell was 20. While reasserting Rose Tyler's age of 19, which is stated in Dalek, the Ninth Doctor's age is given as "unknown".