Six downloadable content (DLC) packs have been released for the 2010 action role-playing video game Fallout: New Vegas, developed by Obsidian Entertainment and published by Bethesda Softworks. Of these, four include map expansions and new storylines. These plots coincide and are ultimately brought together in the final major DLC of the four, Lonesome Road.

Dead Money Dead Money is the first Fallout: New Vegas downloadable content pack and takes place at the Sierra Madre, an isolated location near the Grand Canyon, consisting of a compact planned town built next to a large casino. The story is a heist-style plot revolving around breaking into the casino's well defended vault, with an overarching theme of letting go and beginning again. The pack adds a new map, along with several new weapons and non-playable characters. Additionally, multiple unique in-game hazards force the player to take a slower and methodical approach: a cloud of poisonous toxin present throughout many areas slowly drains health points; wall-mounted speakers emit radio frequencies that can trigger an explosive collar around the player's neck if they linger by one for too long, instantly killing them; and invincible holographic enemies patrol interior locations on set paths, requiring the player to avoid them by timing movements or changing the patrol patterns via terminals.

The expansion was released on December 21, 2010 for Xbox Live, and February 22, 2011 for the PlayStation Network and Steam.

Plot In the mid-late 2070s, with threats of nuclear war rising, businessman Fredrick Sinclair vowed to create a self-sufficient, impenetrable safe haven for actress Vera Keyes, for whom he harbored deep feelings. As such, he built the Sierra Madre Casino & Resort. The scientific research company Big MT was contracted to supply experimental technology for the project, including holographic security guards, heavy-duty hazmat suits, and matter replicators. Secretly, they also decided to use the site as a testing ground for an airborne toxin. To Sinclair's dismay, he learned that Keyes was involved in a plot (albeit unwillingly) organized by lounge singer Dean Domino to rob the casino vault. Angered, he had the vault built to trap an intruder inside, but felt remorse after Keyes confessed to him. He attempted to personally disarm the trap, but succumbed to the lethal toxin in the air systems before he could.

Shortly after, global nuclear war between the United States and China erupted. Guests present for the casino's intended grand opening were mistaken by the holographic security for intruders and slaughtered, while Keyes chose to commit suicide by overdosing. The only survivors were Domino and several construction workers wearing the hazmat suits. The latter were unable to free themselves as a result of the suits' overengineered design and mutated due to the toxin, becoming known as the "ghost people". Over the next two centuries, the toxin cloud expanded to envelop nearly the entire complex; its lethal nature deterred most explorers and left the site largely untouched. Domino, now ghoulified, remained behind, still desiring to break into the vault.

A little more than 200 years later, Father Elijah — a rogue Brotherhood of Steel elder — arrived at the Sierra Madre, looking to use its experimental technology to wage a one-man war against the New California Republic (NCR), but found that he also needed to unlock the vault to achieve his goals. Using a nightkin (a variant of super mutant) with multiple personalities named Dog and God, he would abduct unsuspecting wanderers, attach explosive collars around their necks, and force them to try to break into the casino. By 2281, all attempts so far have proven unsuccessful. His latest captives are Domino and a woman named Christine Royce — an operative sent by the Brotherhood to eliminate Elijah.

The Courier is drawn to an abandoned Brotherhood bunker by a mysterious radio broadcast, only to be rendered unconscious and brought to the Sierra Madre. There, they wake up collared and stripped of all possessions. The player is forced by Father Elijah to form a makeshift team with Domino, Royce, and Dog/God in order to trigger the casino's original programmed grand opening event, which unseals the main doors. All the while, they must contend with the ghost people, toxin cloud, and security holograms. Once inside, the player restores the building's power. Afterwards, they confront each member of the team and decide their fate. The Courier then enters the casino's lower levels, reaching the vault and luring Elijah down to it via the intercom system. There, they can choose to kill him or trap him inside.

Alternatively, in two non-canonical endings, the player can ally themselves with Elijah or become trapped in the vault themselves.

Reception Dead Money received mixed reviews from critics, on Metacritic scoring 70 for both PC and Xbox 360, and 68 for PS3. Kristine Steimer of IGN praised the slower-paced gameplay and the fact the player is required to meticulously search for supplies while avoiding enemies, but acknowledged the existence of several major bugs that negatively affected the user experience. She also criticized a sudden jump in difficulty, stating, "there’s also a random difficulty spike halfway through that can be really frustrating. The game switches from a stealth focus to combat-heavy, but with such limited ammo and supplies, fighting off waves and waves of overly aggro ghosts isn't much fun."

Honest Hearts Honest Hearts is the second downloadable content pack for Fallout: New Vegas. It is set within Zion National Park in Utah and features four factions: the Dead Horses, the Sorrows, the White Legs, and the New Canaanites. The first two tribes peacefully inhabit Zion together, while the White Legs are hostile invaders who know only how to survive off of raiding. The New Canaanites are Mormon missionaries who lend their assistance to the Sorrows and Dead Horses. The story explores several religious themes and encourages the player to choose between two sides trying their best to do what they believe is right. The pack includes a new map to explore, along with new weapons, non-playable characters, and wearable outfits.

The expansion was released on May 17 and May 18 of 2011 for Xbox Live and Steam; however, the PlayStation Network release did not come until June 2 of that year due to the 2011 PlayStation Network outage

Plot In the mid-23rd century, Joshua Graham, a Mormon missionary from the post-war settlement New Canaan, located near the ruins of Salt Lake City, met a man named Edward Sallow. The two encountered the post-war Blackfoot tribe, taught them the concept of total warfare, and molded them into a formidable fighting force. They went on to form the totalitarian dictatorship Caesar's Legion, modeled after the Roman Empire, with Sallow as "Caesar", its leader, and Graham as the "Malpais Legate", Caesar's second-in-command. The Legion swept across the former American Southwest, conquering dozens of tribes and assimilating them. In 2277, however, the Legion battled the NCR for control of Hoover Dam and lost. As punishment, Graham was stripped of his position, set on fire, and thrown into the Grand Canyon.

A remorseful Graham would ultimately survive and return to New Canaan. Sightings of the "Burned Man" reached Caesar, who recruited the White Legs — a tribe aspiring to voluntarily join the Legion — into destroying the Mormon settlement. The survivors, including Graham, migrated south to Zion National Park where they met the region's tribes: the Dead Horses and the Sorrows, who they vowed to protect from the still pursuing White Legs. Graham assumed the position of the Dead Horses' war chief, while fellow missionary Daniel assisted the Sorrows. The two Mormons hold differing viewpoints, with the former wanting to stay in Zion and militarily defend against the White Legs, while the latter wants to evacuate both tribes to the Grand Staircase in order to preserve their peaceful nature.

In 2281, the Courier accompanies a caravan from the Mojave Wasteland through Zion and comes under attack by the White Legs, of which they are the only survivor. Lacking the knowledge of how to get back, they venture into the national park, meeting Graham and Daniel, who both ask the Courier to gather supplies for their respective plans. The player must decide to either fight the White Legs alongside Graham, or assist Daniel in fleeing Zion. At any point throughout the story, the player can choose to turn on both the Sorrows and the Dead Horses, recover a map of the region, and leave early.

Additional exploration of the map allows the player to learn the story of Randall Clark, an ex-soldier who, following the deaths of his wife and son during the Great War, came to protect Zion.

Reception Honest Hearts received mixed reviews from critics, on Metacritic scoring 66 for both PS3 and PC, and 64 for Xbox 360. Dan Whitehead of Eurogamer referred to it as a "survivalist’s dream", due to the main game's traditional healing item, stimpacks, being largely substituted with fruit and meat found around the DLC's map. He praised the inclusion of a unique enemy, the Yao Guai, and a powerful weapon, the She’s Embrace, but critiqued the quest designs, describing them as being non-optional fetch quests. He further stated that he found the ending simple and disappointing.

Old World Blues Old World Blues is the third downloadable content pack for Fallout: New Vegas. It takes place at a vast complex filled with scientific laboratories, called the Big MT Research Facility, and nicknamed the "Big Empty"; the primary inhabitants being the lead scientists: doctors Klein, Borous, O, 8, Dala, and Mobius, together known as the Think Tank. The story takes a humorous tone and revolves around the concept of the pursuit of science with no ultimate practical benefit. The pack features new enemies and weapons, along with a new map.

The pack released on July 19, 2011 for Xbox Live, the PlayStation Network, and Steam.

Plot In the 21st century, Big MT served as a defense contractor for the United States military, creating numerous pieces of experimental technology, such as bodysuits able to override the motor functions of injured soldiers and return them to base, a durable ceramic-like polymer alloy called "Saturnite", cyborganic weaponry, and artificial weather, among other things. Their methods were highly unethical, however, with test subjects frequently being sourced involuntarily, including from captured Chinese soldiers in the ongoing Sino-American War. Following the Great War, the Think Tank continued their work, instead obtaining test subjects from wastelanders who stumbled across the Big Empty. These unfortunate people, known as "lobotomites", had their spines, hearts, and brains replaced with electronic equivalents in order to prevent them from escaping, as only a functioning brain was able to penetrate the radar fence surrounding the complex. These procedures consequently greatly limited their cognitive abilities.

At some point, the Think Tank transferred their brains from their human bodies into hovering mechanical chassis. Dr. Mobius realized the danger that his colleagues presented to the wasteland and hacked their brains, erasing their memories and all knowledge of the world outside the Big Empty, before trapping them in a recursion loop. He then relocated to a different part of the complex, where he constructed hostile robotic scorpions to attack the Think Tank and keep them distracted.