This is a semi-complete list of characters in the original Source. They are all fictional characters on whom key plot progression is based or otherwise have an important impact on the narrative.
The following characters are either Lozenge's permanent traveling partners or major supporting characters. They are listed in the order that they are introduced.
- Lozenge, introduced in Chapter 1, is an earth pony mare and the lead protagonist of Source. She is a former Apostate terrorist who incurs retrograde amnesia through a failed suicide attempt. She is initially manipulated by the Church to expose her co-conspirators living in Baltimare, but is saved due to the interventions of Spike and Twilight Sparkle. She is torn between following the Church's dogma or forcefully thawing the world by waking Princess Celestia.
- Breakbeat, .
- Dr. Helix
- Dr. Helix .
- Apple Peel
- Apple Peel, .
- Double Down
- Double Down, .
- Sleeves, introduced in Chapter 18, is a Diamond Dog mercenary. She chooses to follow Lozenge after Double Down returns her family badge, formerly the property of her father Hobble, after the latter's death. She becomes an important source of fire support with her ability to use a series of highly destructive weapons designed for Diamond Dogs, including the Apocalimiter.
- Sirocco, .
- Cameo, .
- The LYL-T
- Lozenge's ship, stolen from the Church of Medical Sciences Deep Well laboratories. It's CPU is a cloned pony irremovably built into the vessel's maneframe.
The following characters are listed by faction in the order that the faction is discovered and their importance within that faction.
- Golden Hoop
- Golden Hoop is the unicorn Bishop of Baltimare, and one of the primary antagonists of the story.
- Copper Bar
- Copper Bar is the pegasus Bishop of Baltimare. He is Sirocco's father, insofar as he is his guardian and commissioner.
- Nurse Heartspark
- Lozenge's co-conspirator and Apostate agent infiltrating the Church of Medical Sciences.
- Church of Whispers agent. First poses as archeologist to observe Lozenge.
- Church of Whispers enforcer. Attempts to assassinate Lozenge.
The Autonomous City-State of BittsburghEdit
- Head of the primary mine shaft known as The Pit. Hires Lozenge to clear out the Changelings from Shaft Six.
The Society of CorunEdit
The Bleam City BanditsEdit
The Sol InvictusEdit
- Cult leader of the Sol Invictus. Worships Baleful Sun and is actively facilitating her return.
The Saddle ArabiansEdit
The Snow DogsEdit
- Female Diamond Dog, and leader of the Snow Dogs. Hired by Blood Cherry to protect the homesteaders in Root City. Pup of Hobble.