Convict tattoo

Convict tattoos were used by the Time Lords to mark their prisoners.

Just after he was forced to regenerate by the Time Lords, (TV: The War Games) the Third Doctor had a dragon tattoo on his right forearm. (TV: Spearhead from Space)

When Romana released three hundred prisoners from the prison asteroid, including Grandfather Paradox, their dragon tattoos "snapped" on their arms as they exited stasis. The Seventh Doctor said the tattoos resembled the mark of Cacophony. (PROSE: Christmas on a Rational Planet)

David Joyce had a long serial number tattooed in blue-black ink just inside the cuff of his right arm. It was scarred from a botched attempt at removing it. (PROSE: Unnatural History)

After they realised that their cryogenic systems were too easy to escape, the Great Houses started wiring prisoners' nervous systems into self-repeating time frames via convict tattoos on their upper right arms.

When Demetra Kine broke out of containment and started freeing the other prisoners, her seguaché Mandeema Kweller modified the tattoos with memeodermal imprinting so that Demetra could see and speak through them. They could also bite any part of the wearer's body. Demetra also attached a tattoo to the prison guard Selvynkesh. (AUDIO: Movers)