Tivolians were the inhabitants of the planet Tivoli. They appeared mole-like or gopher-like. Those who knew Tivolians easily grew to dislike them due to their annoying desire to be conquered and their cowardice.
Tivolians were one of the oldest species in the galaxy. Their homeworld was conquered multiple times, giving rise to them deliberately coming up with anthems to appease their new conquerors and even making their cities comfortable with whomever took them over. (TV: The God Complex)
The Fisher King invaded Tivoli with his armies in the mid-20th century, ruling for ten "glorious" years before being overthrown by the Arcateenians. Dismayed at having been liberated, the Tivolians proceeded to irritate the Arcateenians so much they chose to enslave them as well. Faking his death, the Fisher King's "body" was taken to Earth in 1980 by funeral director Albar Prentis to be buried in accordance with Arcateenian custom which required him to be sent to a "barren, savage outpost." Prentis was among those killed by the Fisher King and converted into a transmitter ghost as part of his a plan to summon an army to retrieve him, only to be foiled and indirectly killed by the Twelfth Doctor shortly after. (TV: Before the Flood)
One Tivolian, a town planner named Gibbis who was engaged in a project to line all his planet's highways with trees so invading armies could march in the shade, was plucked from his homeworld and deposited in a hellish "hotel" where people were made to face their greatest fear, with Gibbis' fear being the Weeping Angels. Gibbis ultimately survived the ordeal and, after his escape from the hotel, requested the Eleventh Doctor drop him off in the TARDIS at the nearest galaxy. (TV: The God Complex)
At first glance, the Tivolians were a society of cowards who had grown so used to being conquered and occupied by other races it had become a way of life just to accept it. They never defended themselves and did everything they could to make their conquerors as comfortable as possible. The Eleventh Doctor considered this to be an aggressive form of cowardice. The Tivolians didn't fight; they survived by outliving their conquerors. Though they did have an underhanded side that went with their survival, they could be easily persuaded to go against the wishes of others; thus Gibbis released Howie despite express instruction from the Doctor. (TV: The God Complex) Remembering his previous experience, the Twelfth Doctor shared the same negative view of the Tivolians, telling Prentis that he wasn't "a fan". Prentis understood the Doctor, stating his people did "tend to antagonise". The Doctor even added that Tivolians wouldn't even say "boo" to a goose, going on to say that they'd even give their car keys and bank information to the bird. Bennett considered Prentis "an idiot" for favouring enslavement. Prentis showed he was willing to ask to be enslaved if he met someone superior to the current occupants of Tivoli. (TV: Before the Flood)