Pacifism

Pacifism was the term used to describe the beliefs of anyone who opposed wars and the use of violence. Anyone who took this choice of life was known as a pacifist.

Pacifist species
After the neutronic war that mutated its survivors, the Thals became a pacifist race. (TV: "The Ambush") The First Doctor wanted them to attack the Daleks, telling his granddaughter Susan that it was "no time for morals". (TV: "The Expedition")

During the human-Hath War on Messaline in 6012, there was an outbreak of pacifism among the humans in the Eastern Zone, three generations before the Tenth Doctor's arrival. (TV: The Doctor's Daughter)

The Arbitans were pacifistic until the Voord forced them to fight. (TV: The Keys of Marinus)

Rills only fought when attacked and were left with no other options. (PROSE: Galaxy Four)

The Dulcians outlawed wars. (TV: The Dominators)

The Humanoid Daleks were pacifists before their leader, Drenz was murdered by the Dalek War Minister, Zolfian. (COMIC: Genesis of Evil)

After the Cybermen became Cyberlords, they were pacifists. (PROSE: Synthespians™)

The Telphin became pacifists after it was "banished from their culture". (COMIC: Memorial)

The Thains were pacifists to the point of having no weapons save in their museum. This left them unable to defend themselves when the Kleptons attacked their city. (COMIC: The Klepton Parasites)

Pacifist individuals
Herrick branded Orfe a pacifist as he had no wish to take up arms against the Time Lords. (TV: Underworld)

The Doctor was a pacifist,  although in his earlier incarnations  he didn't show a hatred for the use of weapons. (COMIC: Master of Spiders)

Sarah Jane Smith often expressed her dislike for violence. (TV: Invasion of the Bane, TV: The Stolen Earth)