Higher species

"Higher species" or "higher forms" was a term used to refer to species who were aware of the Time Lords and the Last Great Time War. Doubting the Tenth Doctor's identity as a Time Lord, the Shadow Architect stated that the Time Lords were the "stuff of legend" and that they belonged in the "myths and whispers" of the higher species. (TV: The Stolen Earth)

According to the Gelth ambassador, the Last Great Time War was devastating to "higher forms" yet invisible to "smaller species", (TV: The Unquiet Dead) the War Master noting that the higher beings were aware of the danger to reality. (AUDIO: Concealed Weapon)

Following the conclusion of the Time War, the conflict was time locked by the surviving higher species. Having seen that the War had nearly destroyed the entire universe and themselves, the higher species wanted to make sure no individual or faction from the new post-War universe could time travel into the conflict to try change or interact with its outcomes, believing that interfering with the conflict would be a danger to the integrity of the Time Vortex (PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe) and the universe. (PROSE: The Secret Lives of Monsters) According to another account, the war was time locked by the Doctor. (COMIC: Don't Step on the Grass, et. al)

Awareness
Even before the Time War, the Time Lords were known to several races and beings. Early in their history, the Time Lords led alliances such as the Fledgling Empires (TV: The Runaway Bride) and the Alliance of Races, the latter of which included the Hath, the Ice Warriors, the Judoon, the Silurians, the Sontarans, Vigil and the Zygons. (COMIC: Terrorformer, Gangland) The Time Lords later formed the Temporal Powers, which included the Monan Host, the Nekkistani, the Virgoans (AUDIO: The Apocalypse Element) the Princessipality of Yevnon, (AUDIO: Pandora) humans, the Warpsmiths of Phaidon, the Sunari (AUDIO: Insurgency) and the Unvoss. (AUDIO: Square One)

Ancient enemies of the Time Lords included the Great Vampires (TV: State of Decay) the Hyperions (COMIC: Terrorformer) and Count D'if of the Cybock Imperium, whom fell to the Alliance of Races, (COMIC: Gangland) and the Racnoss, who fell to the Fledgling Empires. (TV: The Runaway Bride)

Other beings and races who were aware of the Time Lords included the Trickster of the Pantheon of Discord, a time-active being, (TV: The Wedding of Sarah Jane Smith) Eldrad, whose native time was 150 million years before the 20th century, (TV: The Hand of Fear) Sutekh, whose native time was 7000 years before 1911, (TV: Pyramids of Mars) and the Daleks by the aftermath of the Dalek Civil War. (PROSE: Doctor Who and the Day of the Daleks) While not all Eternals were aware of the Time Lords, (TV: Enlightenment) some passed themselves off as Gallifreyan deities. (PROSE: Happy Endings) Andromeda native Sabalom Glitz suspected the Sixth Doctor of acting on their behalf circa 2000000. (TV: The Mysterious Planet) The CyberNeomorph faction of Cybermen were aware of the Time Lords and that they were forbidden to interfere, (TV: Earthshock) the Cyber-Controller even claiming that if the Sixth Doctor could warn the Time Lords, they could not stop the Cybermen. (TV: Attack of the Cybermen) House, who had killed many Time Lords outside of N-space, was unware that they seemingly perished in the Time War. (TV: The Doctor's Wife)

The Vardans were used by the Sontarans in their attempted invasion of Gallifrey. (TV: The Invasion of Time) The Dominators once sent their robotic servants, the Quarks, to attack the Capitol. (AUDIO: Time in Office)

Having been caught in their Time War, the Time Lords were recognised by the Nestene Consciousness, (TV: Rose) the Gelth, (TV: The Unquiet Dead) and the Bygone Horde. (AUDIO: The Other Side)

In 1980, the Fisher King described the Time Lords to the Twelfth Doctor as "cowardly, vain curators who suddenly remembered they had teeth and became the most warlike race in the galaxy." (TV: Before the Flood)

In 2007, Brother Lassar of the Krillitanes was aware of the Time Lords and their apparent extinction. (TV: School Reunion)

In 2010, the Shansheeth recognised the Eleventh Doctor as the last of the Time Lords. (TV: Death of the Doctor) After news of the Doctor's death at Lake Silencio in 2011 spread, recognised her new position as "the last of the Time Lords." (AUDIO: The Bekdel Test)

The time travelling Family of Blood recognised the Tenth Doctor as the last of the Time Lords. (TV: Human Nature / The Family of Blood)

Shortly before his death in 4221, the Beast branded the Tenth Doctor as "the killer of his own kind". (TV: The Satan Pit)

By the Siege of Trenzalore, "half the universe" lay in wait over Trenzalore, ready to restart the Time War had the Time Lords returned. They included Daleks, Cybermen, Weeping Angels, Sontarans, Terileptils, Slitheen, Silurians, Judoon, Ice Warriors, Krynoids, Nestenes, Shakri, Krotons, Mara, Monoids. The Church of the Papal Mainframe, which included humans and Silents, fought in defence of the planet alongside the Eleventh Doctor. (TV: The Time of the Doctor)

By Earth Death in 5,000,000,000, Jabe of the Forest of Cheem was aware of the apparent extinction of the Time Lords at the end of the Time War, and was surprised when she found that the Ninth Doctor was one. (TV: The End of the World) The Face of Boe also knew the Tenth Doctor to be a Time Lord. Immediately prior to his death in 5,000,000,053, he informed the Doctor, who believed himself to be the last of his kind at the time, that he was not alone. (TV: Gridlock)

Behind the scenes
The Dalek Handbook acknowledges the Forest of Cheem, the Nestenes, the Gelth, the Greater Animus and the Eternals as Higher Species.