- Kimball "Kim" O'Hara – is an orphan son of an Irish soldier, the protagonist; "A poor white, the poorest of the poor"
- Teshoo Lama – a Tibetan Lama, the former abbot of the Such-zen monastery in the western Himalayas, on a spiritual journey
- Mahbub Ali – a famous Ghilzai Pashtun horse trader and spy for the British.
- Colonel Creighton – British Army officer, ethnologist and spy
- Lurgan Sahib – a Simla gem trader and master spy
- Hurree Chunder Mookherjee (Hurree Babu, also the Babu) – a Bengali intelligence operative working for the British; Kim's direct superior
- the Kulu woman (the Sahiba)- an old hill Rajput noble lady settled near Saharanpur in the plains.
- the Woman of Shamlegh (Lispeth) who helps Kim and the Lama to evade the Russian spies and return to the plains
- the old soldier – a Sikh Risaldar (native officer) who had been loyal to the British during the Mutiny.
- Reverend Arthur Bennett – the Church of England chaplain of the Mavericks, the Irish regiment to which Kim's father belonged
- Father Victor – the Roman Catholic chaplain of the Mavericks
- a Lucknow prostitute whom Kim pays to help disguise him
- a Kamboh farmer whose sick child Kim helps to cure
- Huneefa – a sorceress who performs a devil invocation ritual to protect Kim
- E.23 – a spy for the British whom Kim helps avoid capture
Her Majesty's Royal Loyal Musketeers, also known as "The Mavericks" is a fictional Irish Regiment of the British Army also mentioned in the novella "The Mutiny of the Mavericks".
The nickname is from the Bull in their colors. Mavericks are stubborn, unbranded cattle that are hard to keep in the herd, much like the independent-minded troops of the regiment. They seem to be a tough regiment with a fierce reputation because in "Kim" they are respectfully known by the natives as the "Red Bullock Men".
Cap Badge: A crowned gold Irish Harp.
Regimental Badge: A red Bull furieux [A Heraldry term that combines the terms Salient (depicted rearing upon its hind legs and striking with its hooves) and Enragé ("maddened" - depicted red-eyed, nostrils flared, and baring its teeth)].
Regimental Colours: A white field with the Cap Badge set in the center on a blue rounded and the red Bulls set in the corners.
Battle Honours (Mentioned in "The Mutiny of the Mavericks"): Vittoria (sic), Salamanca, Toulouse, Waterloo, Moodkee (sic), Ferozshah (sic), Sobraon, Inkerman, The Alma, and Sebastopol (sic).
The battle honours should be listed by date, but some of the battles are out of order. There is also some mention of the Indian Mutiny of 1857 and the wars in Afghanistan in passing, but it is unclear whether they are Honours or just campaigns the regiment served in.