They are designed to be elite killing machines, unlike others of the synth 'race'. They are noted by the Railroad and the Institute to be exceptional even for synths, as they possess exceptional strength, combat prowess, awareness and endurance. They are widely feared by the Railroad, as their first instinct when they see a Courser is to cease all operations and remain low.
Most coursers wear the Courser uniform and usually some pair of sunglasses. Some, but not all coursers, have a stern look on their face with a monotoned voice. All coursers encountered are male, though with different facial styles.
The Synth Retention Bureau is the main organization that the coursers work for. They are the ones who assign coursers their missions to go out to the surface via relay from their courser chip which allows them to have a form of teleportation. The SRB primarily uses Coursers to retrieve and reset escaped synths, with deadly efficiency.
According to Justin Ayo, Coursers are trained from Generation 3 Synths, though not all trainee Coursers may pass. Those who pass will be inducted as Coursers, while those who fail will have their memory about the training brainwashed and reassigned.
Greenetech Genetics - This is the location where the Sole Survivor will meet their first Courser; Z2-47. This Courser is after a runaway Synth, and is killing anyone in his path. The Survivor begins to chase him throughout the base, and fighting through the still alive Gunners the Courser left behind.
- X6-88 - X6-88 is a possible companion who is assigned to the Sole Survivor in Synth Retention. He is available as a companion after Mankind-Redefined. He also appears in Kellogg's memories.
- X9-27 - X9-27 is a Courser encountered above ground, he is in the process of completing orders given by The Institute. He is encountered during the Operation Ticonderoga quest.
- Z2-47 - Z2-47 is seeking a runaway Synth, killing multiple Gunners in his path and not slowing down. He must be killed for Hunter/Hunted.
- X4-18 - During the quest The Battle of Bunker Hill, X4-18 is found waiting for the arrival of The Sole Survivor
- Harkness (A3-21) - 情報は少ないが、現在ある情報からしてハークネスはコーサーであった可能性が高い。現在はリベットシティに居ます。 The Replicated Manでは、Doctor Zimmerが彼を回収しようとしています。
- A courser may call in Synth reinforcements during combat, which will appear in the form of three randomly armed Gen 1 Synths. Killing a Courser before initiating combat (e.g sneak attacks) will still spawn these Gen 1 Synths.
- During the first visit to the Institute during Institutionalized, a random Courser can be observed talking a nameless Gen 3 Synth about accessing a prohibited terminal, threatening her with a memory wipe. The Courser will be convinced of the Synth's explanation, however.
- If the player character completes the mission at Libertalia for the Institute, random Coursers in the Institute will comment on how X6-88 admires the player character's combat skills, suggesting that Coursers socially communicate with each other or that coursers keep and publish reports of their missions.
- Coursers appear to possess an even more advanced AI than the newest generation synths. This can be observed during the final affinity dialogue with X6-88, in which he states that he had tremendous doubts about the player character's abilities. Through a miscellaneous dialogue with Justin Ayo the player character is hinted that Coursers are heavily brainwashed and altered when compared to the normal synths.
- While female synths are encountered in the game, coursers are seemingly all male.
- Many facets of the Courser concept - such as their being extremely advanced artificial assassins, wearing dark uniforms and sunglasses, displaying next to no emotions in dialogue and being considered exceptionally dangerous to the point where everyone is advised to flee from them rather than face them in combat - give them a striking similarity to the Agents from the Matrix franchise. They also share similarities with the eponymous robot predators of the Terminator series.
- The origins of Coursers remains somewhat unclear due to contradicting information. According to Justin Ayo, Coursers are normal Gen 3 synths who are superior than their peers who are inducted. However, a large amount of other sources claim that Coursers are built specifically for the purpose of synth retrieval.