He is hired by Agent Church in the first film to investigate suspicious activities on the island of Vilena and take out its fanatical dictator, General Garza.
Barney considers abandoning the job after finding out that renegade CIA agent James Munroe is using Vilena as a source of narcotics production.
Though Barney completes his assignment, Church wants compensation for the death of Munroe and hires the Expendables in the second film to recover a briefcase containing sensitive information from a downed plane in Albania .
Vilain murders Barney's rookie crew member Billy the Kid and takes the briefcase, which contains a computer map revealing the location of five tons of discarded plutonium.
In the third film, Barney and his crew, now reinforced by veteran member Doctor Death, are sent to take down an arms dealer who turns out to be Expendables co-founder Conrad Stonebanks.
Barney is tasked by CIA agent Drummer to arrest Stonebanks and deliver him to the Hague for war crimes; Ross subsequently forms a new Expendables team, disbanding the former members.
Barney is very close to his teammates and often worries over their safety, showing great remorse over the death of Billy the Kid and even disbanding his former team after Hale Caesar is hospitalised.
His signature weapon is a revolver pistol, which he keeps hidden in a holster behind him in order to take targets by surprise, and is also an expert pilot.
Trent "Trench" Mauser, portrayed by Arnold Schwarzenegger, is the head of a competing mercenary group who turns down the job offer from Church in the first movie.
Trench, Church and the Expendables collectively take down the Sangs and Vilain, who are trying to escape Albania with 5 tons of weaponized plutonium.
During the finale Agent Drummer, Trench and Yin Yang provide support for the Expendables as they are attacked by the Asmenistan army, controlled by Stonebanks.
He is often seen smoking a cigar, a real habit of Schwarzenegger's, and he delivers several lines that are either related to or directly taken from his prior action-movies.
Lee Christmas, portrayed by Jason Statham, is a former SAS soldier, Barney's closest friend and right-hand man on the Expendables team.
Yang is seen at the start of the second film helping to rescue Trench Mauser and an unnamed Chinese hostage (presumably he was being held for ransom, as he is referred to as "moneybags" by Christmas) but leaves the team to escort the billionaire back to China while the others return to the US.
Wesley Snipes was originally offered the role of Hale Caesar, but was forced to turn it down due to serving a three-year sentence for tax evasion, which is referenced in the third film.
Gunner is later hired by James Munroe to provide intel on Barney and the Expendables when they begin disrupting his drug operation in Vilena.
When he returned to base, he found that his superior officers had ordered a stray dog he had adopted be put down; seeing this as yet more pointless violence, an angered Billy resigned from the military and eventually joined the Expendables.
Thorn is also shown to be an expert rock climber, and uses his skills to climb an unfinished elevator shaft unassisted towards the film's end.
Later, when Barney goes after Stonebanks with his old crew, Drummer takes Trench and Yin Yang along as support; he is shown to be a capable helicopter pilot.
Despite Stonebanks' death, he seems to be in good spirits meeting Barney after their escape from Azmenistan, commenting "I haven't had this much fun in years".
Ford makes several meta jokes commenting on Church's absence (stating that he is "out of the picture"), Stallone's stroke and Jason Statham's heavy accent.
Barney deduces that Church has been turned down by all other mercenary groups, including Trench Mauser at their first meeting, which is why he demands $5 million, and that half of this be paid in advance.
Though Barney and his crew complete Church's assignment, he holds a grudge over the death of James Munroe, a rogue agent and the true mastermind behind Garza's coup.
In truth, Willis did not appear due to disagreements with Stallone over his salary, which led to his role being retooled for the character of Drummer and the casting of Ford to replace him.
While his screen time in the film is limited, Tool plays a crucial role in the plot nonetheless; he confesses to Barney that he allowed a woman to commit suicide instead of saving her during a mission in Bosnia.
Introduced in the second film, she is assigned to work with Barney and the rest of the Expendables to fly down to Albania and retrieve a program that carries access to plutonium.
His private life is also troubled, as his daughter Sandra regards him as a coward; she actively works against him by assisting Barney and Lee in their reconnaissance of the island.
Conrad Stonebanks, portrayed by Mel Gibson, is an arms trader and co-founder of the original Expendables, and was introduced in the third film as the main antagonist.
He was originally presumed dead, but was revealed to be alive when he was seen delivering a shipment of bombs to warlords of Somalia under the alias Victor Minz.
Stonebanks is then captured by Ross and the new team members, and they attempt to bring him in a van to the International Criminal Court by orders of CIA operative Max Drummer.