All Agents are Caucasian males (with a minor exception of female Agent Pace from the Matrix Online game), which also provides a dynamic compared to the majority population of Zion, containing many diverse cultures and walks of life. Agents wear dark sunglasses with corners or smooth angles. The Caucasian male Agents simply show a blandness and an apathy for the human race, with the exception of Smith's obsession with destroying Neo and his general hatred of humans.
Other Agents have names like Brown, Johnson, and Thompson — common, innocuous, Anglo-Saxon names. It was mentioned in the Philosopher Commentary on the DVD collection that the names of Smith, Brown and Johnson may be endemic to the system itself, demonstrating a very 'robotic' mindset on the part of the Machines.
"Behold, I have created the smith that bloweth the coals in the fire, and that bringeth forth an instrument for his work; and I have created the waster to destroy."
In creating such a program to carry out menial tasks, the Machines lay the foundations for their own destruction, a direct parallel to the creation of AI by humankind.
Neo's solitary role as The One is contrasted by Smith, who, by replicating himself, becomes 'the many'. When Neo asks the Oracle about Smith, the Oracle explains that Smith is Neo's opposite and his negative.
Smith's weapon of choice, as standard with all the Agents within the Matrix, is the Desert Eagle, chambered with the high caliber .44 Magnum (determined by the number of rounds fired from the gun) ammunition. All his clones carry this weapon as well. In the first film, Smith is shown killing Neo with the gun, however the number of times he fires it in this scene exceeds the actual capacity of the .50AE Desert Eagle, which is seven rounds.
Unlike the other characters in The Matrix, Smith almost always refers to Neo as 'Mr. Anderson.' He calls him 'Neo' only once in each part of the trilogy. (The first time when he is interviewing Neo about his double life, the second when he is dropping off an Agent earplug in a package for Neo and the third when he is repeating a line of his vision to his face.)
Agent Smith complains that the Matrix and its inhabitants smell disgusting, "if there is such a thing [as smell]". Smith has an open hatred of humans and their weakness of the flesh. He compares humanity to a virus, a disease organism that would replicate uncontrollably and eventually destroy their environment were it not for the machine intelligences keeping them in check. Ironically, Smith eventually becomes a literal virus, multiplying until he has overrun and remade the entire Matrix.
During Morpheus' imprisonment:
I’d like to share a revelation that I’ve had, during my time here. It came to me when I tried to classify your species and I realized that you aren’t actually mammals. Every mammal on this planet instinctively develops a natural equilibrium with its surrounding environment, but you humans do not. You move to an area and you multiply, and multiply until every natural resource is consumed. The only way you can survive is to spread to another area. There is another organism on this planet that follows the same pattern. Do you know what it is? A virus. Human beings are a disease, a cancer of this planet. You are a plague, and we... are the cure.
At the same time, Smith also secretly despises the Matrix itself, feeling that he is as much a prisoner of it as the humans he is tasked with watching over. He later develops an immense and increasingly open desire for the destruction of both mankind and machines alike.
Smith also appears to be the leader of other Agents, in that he has the authority to launch Sentinel attacks in the real world. As with other Agents, Smith generally does approach problems through a pragmatic point of view, but if necessary will also act with brute force and apparent rage.
The Wachowski brothers have commented that Smith's gradual humanization throughout The Matrix is a process intended to mirror and balance Neo's own increasing power and understanding of the machine world.
The idea of Smith's transformation from being an Agent of the System into becoming a "free Agent" is similar to Satan's Fall from Grace. In both cases, a former Agent of the System (in the two sequels, Smith is no longer referred to as "Agent Smith", but simply as "Smith") becomes able to move freely, and comes to have a dangerously rebellious and opposite nature. The virus-like qualities he gains may also be a reference to this, as one of the traditional titles of a demon is Legion, for they were many.
Agent Smith appears to have been destroyed by Neo at the end of the first movie in The Matrix trilogy, but he makes a calculated return in The Matrix Reloaded with somewhat altered abilities and motivations, in addition to dropping the title "Agent". His appearance has changed from the first movie as well; his sunglasses are of a different, more angular shape than the square ones the Agents wear and his suit is now black instead of dark green (Matrix code): physical signs of his connection with Neo. Smith also lacks the earpiece most Agents wear on their right ear, showing he is now "unplugged". Smith loses his ability to phase into any body connected to the Matrix at will, as he is no longer directly a part of the system. Instead, Smith is now infectious through touch; by jabbing his hand into the body of another being in the Matrix, a Smith can convert that being into another Smith, replicating himself in much the way a computer virus might.
In The Matrix Revolutions, Smith's presence in the Matrix has consumed all of the "Core Network" (the underlying foundation of the inner workings of the Matrix), thus rendering him immutable by even the machines themselves. The Oracle explains to Neo that he and Smith have become equal in power, and that for Smith to be eliminated, the equation must be "unbalanced". Smith has already begun absorbing all the inhabitants of the Matrix; every single human being plugged into it, and every single program functioning inside it, including the Oracle. When he absorbs the Oracle, the process apparently granted him her powers of foresight, as well as reality-bending powers equivalent to those possessed by Neo. Towards the end of the movie, Neo engages a single Smith, in a seemingly endless struggle between two forces of equal might. The other Smiths do not participate, because Oracle/Smith explains he has foreseen that he is the Smith that will beat Neo. In the midst of this battle, Smith explains to Neo his final nihilistic revelation, he has come to learn from Neo ("It was your life that taught me the purpose of all life.") that "the purpose of life is to end." Smith also intended to conquer the real world as well, and had Neo not defeated him he would have succeeded in escaping the Matrix, taking over the machines, and destroying Zion itself.
After an arduous battle in midair, Neo is smashed into the ground by an enraged Smith, making a large impact crater. Smith asks why Neo fights when he knows he will lose: "Is it freedom or truth? Perhaps peace? Could it be for love?", reasons which he believes are
temporary constructs of a feeble human intellect trying desperately to justify an existence that is without meaning or purpose, and all of them as artificial as the Matrix itself. You must be able to see it, Mr. Anderson, you must know it by now. You can't win, it's pointless to keep fighting. Why, Mr. Anderson, Why, why do you persist?Smith is enraged by Neo's simple and irrational answer: "Because I choose to".
Ultimately, Smith prevails, beating Neo unconscious. Suddenly recognizing the scene from the prophecy, he stands before Neo and says, "Wait... I've seen this... This is it, this is the end! Yes, you were lying right there just like that and I... I... I stand here, right here and I'm... supposed to say something..." In a moment of confusion, Smith reveals that he is merely following what the prophecy tells him he should do. In spite of his gaining the oracle's vision, he remains blind. He continues on, regaining his composure.
"I say... Everything that has a beginning has an end, Neo". This is the only time that Smith does not call him "Mr. Anderson" to his face , and Smith displays noticeable confusion after this, apparently not knowing what he has just said. This suggests that it is the Oracle within Smith and not Smith himself who speaks here. Unable to overpower Smith, Neo understands that he will never beat him in this way. He surrenders to Smith, who absorbs him, seemingly conquering his enemy.
The "absorption" is not one-sided, with either force conquering the other. Rather, there is a union of opposites, of thesis and antithesis, leading to the synthesis of the new beginning, in which the Matrix, with its equation of oppression and control, is unbalanced. Because Neo has been connected to the Matrix by the "god of machines" itself, the union between Smith and Neo results in Smith's being directly connected to the machine god, allowing him to finally be deleted.
After Neo knocks Smith into the crater in the level "Aerial Battle", Smith is sent flying through the ground and up through the street. As Neo relaxes, the surrounding Smiths walk away from the crater. Neo gets out of the crater, and dodges a car which flies through the air and lands in a pile of debris. Neo looks on as Smiths tear up chunks of the road and throw cars into this pile. A truck then speeds into a building and blows it up. Smiths can be seen holding the debris together as it takes on a thirty-story tall humanoid form which is then struck by lightning, powering it up. Neo flies up to watch as the giant humanoid lowers its head onto its shoulders. The giant Smith then pulls a pair of giant Smith Shades from a billboard and puts them on. As an interesting aside, the glasses on the billboard are the same ones Agent Smith wore in the first Matrix film, with the curved nosebar, but when the MegaSmith actually puts them on, they've suddenly turned into the ones Agent Smith wears in The Matrix Reloaded and Revolutions, with the straight nosebar and a different shape.
After the fight, Neo flies straight into MegaSmith's mouth, causing the Smiths throughout the Matrix to overload and explode. We then cut to a shot seen in The Matrix: Revolutions of the streets shining with light from the destroyed Smiths.
The most recent appearance of the Smith virus was during the third anniversary events. The virus manifested itself in the form of black-suited men (although they lacked the distinct likeness of Smith). As redpills began to fight back using specialist code from the Oracle, the virus vanished suddenly, stating he had obtained a new and more dangerous form. What this form is remains to be seen, though it evidently means Smith will return to attempt to retake the Matrix.
After being freed from the control of the machines, Smith learned that he can copy his programming into bluepills, redpills and other programs, thus making numerous clones of himself. Smith used these copies to battle Neo and other redpills on multiple occasions. This power leads to him being the arguably most powerful program towards the end of the series. His different forms are shown to have vastly different abilities as to reflect the original programs/persons that he had overwritten. This is most clear through the extremely powerful Smith originating from the Oracle who beats Neo in a one on one combat. Smith seems to keep some memory from the original subject during the copying process as he quotes Sati.