Armour

Armour was worn by many species for protection.

By humans
Ashildr recalled penetrating armour during the Battle of Agincourt. (TV: The Woman Who Lived)

By Daleks
As the Ninth Doctor explained, Dalek mutants resided within their casings, which served as battle armour. (TV: Dalek) According to the Seventh Doctor, this armour was composed of bonded-polycarbide. (TV: Remembrance of the Daleks) As the Third Doctor noted, the Daleks' armour acted as a shield. (TV: Planet of the Daleks)

used a dark star alloy brooch to penetrate a Dalek casing, noting that it went through armour plating like "a knife through people". (TV: The Witch's Familiar)

By Cybermen
As Yvonne Hartman observed, the Cybermen of Pete's World converted humans by removing their brains and placing them in a suit of armour. (TV: Doomsday) Mercy Hartigan refered to these Cybermen as her "knights in shining armour, quite literally." (TV: The Next Doctor)

Aboard a Mondasian colony ship, the Mondasian colonists initially lacked guns that could shoot through the armour of the advanced Cybermen. However, Nardole was able to modify the Mondasian's rifles to provide a defense. (TV: The Doctor Falls)

By Ice Warriors
As explained by the Eleventh and Twelfth Doctors, the Ice Warriors constructed and wore bio-mechanical survival armour for protection so they could exist in the freezing cold of their homeworld, Mars. The former characterised them as becoming bio-mechanoid cyborgs, while the latter observed "the creature within is at one with its carapace." (TV: Cold War, Empress of Mars)

As noted by the Eleventh Doctor, a sudden increase in temperature, such as being struck by a cattle prod, sent the armour haywire. (TV: Cold War)

By Sontarans
Sontarans wore a distinctive armour which Jingo Linx identified as Sontaran space armour. (TV: The Time Warrior, The Two Doctors)