A veteran soldier of the Systems Alliance Navy, an N7 graduate of the Interplanetary Combatives Training (ICT) military program, and the first human Citadel Council Spectre, Shepard works to stop the Reapers, a sentient machine race dedicated to wiping out all advanced organic life.

Most promotional material for the series focused on the male Shepard, due to the studio's desire for a single identifiable hero, though both versions of the character were given equal priority during development.

Unlike other role-playing game protagonists, they felt Shepard should not be an entirely blank character for the player to create, in order to create a more "intense" experience; with Mass Effect being more cinematic than other BioWare video games, they felt they needed an "extra bit" with a sense of a specific flavor that can be caused by a memorable character, such as Star Trek's Captain Kirk or 24's Jack Bauer.

[17] Meer had first worked with BioWare during the creation of Baldur's Gate II: Shadows of Amn and went on to voice other bit parts in their games.

Different choices on the dialogue wheel can grant either Paragon or Renegade points, which will over time affect their physical appearance in Mass Effect 2 and Mass Effect 3: a higher Renegade score will cause Shepard's scars to worsen and their eyes to start glowing red, while a higher Paragon score will cause Shepard's scars to gradually heal and fade away.

Outside of the main trilogy, Shepard has been briefly mentioned in the novels Mass Effect: Ascension, Retribution, and Deception, and has also made a brief appearance in the third issue of the comic Homeworlds, with only the N7 logo on their armour being shown in-shot.

Redemption, taking place two years before the second game's main events, concerns how Shepard's body was retrieved by Liara T'Soni and then given to Cerberus after the character's death in Mass Effect 2's prologue.

[27][28] In the first game, the commander is serving under Captain David Anderson during the shakedown run of the highly advanced turian/human ship SSV Normandy, heading toward humanity's first ever colony, Eden Prime.

However, Nihlus is killed during the mission when the geth, a race of sentient AIs, and Saren Arterius, a rogue Spectre, attack the colony to steal the beacon.

Depending on the player's choices during the final mission, it is possible that Shepard may fail to escape the Collector base and die, though the save cannot be imported to Mass Effect 3 if this is the case.

Shepard must then work to forge alliances between the various alien races to ensure the survival of Earth, to fight against Cerberus forces from disrupting the war efforts, and to stop the Reapers from eradicating all organic life from the galaxy.

Among the major decisions made by the player as part of the branching narrative of Mass Effect 3 include the resolution of the Krogan Genophage storyline, the outcome of the war between the geth and the quarians, and ultimately the fate of the Reapers and the rest of the galactic community.

The female Shepard was confirmed to be making an appearance in one of the trailers for the third game, and on one side of Mass Effect 3's Collector's Edition, in June 2011.

[41][42] Commander Shepard has received a generally positive reception and often appeared in reader's polls published by video game publications.

[57] Although female Shepard is less popular with players compared to her male counterpart, the character and her voice actress has consistently been well received critically.

[58] Hale was nominated for "Best Performance By A Human Female" at the 2010 Spike Video Game Awards,[59] though lost to fellow Mass Effect voice actor Tricia Helfer (playing Sarah Kerrigan in StarCraft II: Wings of Liberty).

[61] Various media outlets like CNET, ONE37pm and CBR have included Commander Shepard in their lists of top female video game characters.

While commentators like Kirk Hamilton from Kotaku accepted what he perceived to be a legitimately democratic choice, others like Kim Richards from PC Gamer rejected the outcome.

[68] The authors of Bridging Game Studies and Feminist Theories noted that the poll produced "six avatars who have the exact same body shape, but are distinguished by different skin, hair, and eye colour."

"[69] Leandro Lima noted that the manner in which Shepard was included within the marketing campaign for Mass Effect 3 was still problematic for many players, as she is "perceived as very generic in terms of design".

[70] Patricia Hernandez from Polygon felt that the manner which the female Shepard poll unfolded was "strange" and that BioWare's attempts to continue modifying her years after the release of the first game while her male counterpart's appearance remains unchanged is somewhat "off-putting".

Nevertheless, she expressed relief that "in 2021, there’s no vote, no massive fan campaign to get BioWare to even consider highlighting FemShep" in response to the character's prominence in promotional material released for Mass Effect Legendary Edition.