During the Investigator's adventures they encountered characters from all walks of life, from amateur actors, through Italian guides and the charming residents of Nepal. Faced by threats much older and more dangerous they could ever have known they also faced cultist, gods and The King itself!

The Group - an amateur theatrical troupe:

• Michael Gillen - Retired publisher and amateur actor (Acquaintance of Doctor Frederick Bartlett and Estus's friend and companion).
• Hannah Keith - Amateur Actress (sister of Andrew Saunders)
• George Keith - Amateur Actor (husband of Hannah Keith)
• Walter Paige - Amateur Actor
• Jean Hewart- Amateur Actress
• Talbot Estus (deceased) - American novelist, playwright and victim of the King

• Doctor Charles Highsmith - Asylum Superintendent
• Alexander Roby - Poet, cultist and madman, Roby is a dreamer of Carcosa and the key to the King's return to Earth.
• Lucius Harriwell - Incarcerated Madman
• Price and Evans - Asylum Nurses

• Doctor Lionel Trollope (deceased) - Roby family physician
• Grahame Roby - Financier, Alexander Roby's brother
• Detective Inspector Andrew Taylor - of New Scotland Yard
• Delia Hartston - Alexander Roby's former fiancee, now Delia Morrison
• Peter Morrison (deceased) - Abusive husband of Delia
• Vincent Tuck - Private Detective, hired by Grahame Roby
• Michael Coombes (deceased?) - a.k.a The Tall Man; Sinister stalker, Bacon's ex-bodyguard

• Harold Jennings (deceased) - Unfriendly Suffolk farmer
• Montague Edwards (deceased) - Alexander Roby's secret guardian
• Lawrence Bacon (deceased) - Antiquarian, occultist and sorcerer

• Cec Watts (deceased) - Tabloid Journalist
• Henry Lister - Terrified cultist and necrophobe
• Aleister Crowley - Famed Occultist

• Quentin Spence - Poet and Failed Cultist
• Noss of Yhtill - Leather worker from an alien world
• Yolanda - Noblewoman from Cassilda's court

• Wilfred Gresty (deceased) - Writer of letters and spy for the Goatswood cult

• Hillary Quarrie - Estranged wife of Malcolm and priestess of the Goat
• Atkinson (deceased) - Ailing leader of the Goatswood Shub-Niggurath cult

• Paolo Tuminardo - Milanese Guide and young Fascist
• Giuseppe Colombo - Ancient, curmudgeonly Italian Brother of the Yellow Sign
• Thomas Villiers (deceased) - Insane artist and Brother of the Yellow Sign

• Mr Julian Knight - Minor diplomat and lounge lizard, en route to India
• Reverend Ian Gore - Missionary, en route to India
• Mrs Henrietta Tullis - Matronly figure, en route to India
• Mr Stephen Thomas - Quiet, bookish man, en route to India
• Miss Francesca Nicholson - Bright young thing, en route to India
• Miss Patricia Berry - Quiet, shy young lady, en route to India

• Sivakumar Patel - Guide and translator from Bombay
• Jigme Rinzing - Nepalese merchant/guide

• Tsewan Pemba - Tibetan Guide
• Carlo Schippone (deceased) - Graduate student and Himalayan adventurer

• Mayor Ricardo Delnegro (deceased) - Alpini officer and Himalayan adventurer
• Roberto Anzalone (deceased) - Professor of Asian History and Brother of the Yellow Sign
• Malcolm Quarrie (deceased) - Elusive scientist and occultist
• The King in Yellow - Beautiful, yet terrible, alien god