This movie could be classified in the action category but its resemblance to other movies like "Cast Away" and "28 Days Later" could place it in other genres like drama or horror. While Tom Hanks struggles to keep his sanity by talking to a volleyball in "Cast Away," Neville (Will Smith) maintains his sanity through his companionship with Sam, his dog, and through other methods with varying success. Neville's use of adult material, television newscasts, and one-sided discussions with mannequins, are all methods the protagonist employs, in order to ward off feelings of loneliness. The comparison between Chuck (Tom Hanks) from "Cast Away" and Neville in "I Am Legend" can be made between throughout, as both main characters struggle to hold onto some semblance of sanity. However, there is a difference in endings where "I Am Legend" is slightly more action based "Cast Away" sticks to more psychological undertones. Both are a joy to watch.

In the first few scenes of "I Am Legend" Neville is seen driving through the streets of New York, while a spiritual symbol appears, in the form of a butterfly, on a poster. The appearance of butterflies in "I Am Legend" occurs over a half dozen times during the course of the movie. Marley (Willow Smith), Will Smith's daughter in real life, uses hand symbols to signify the spirituality of the butterfly. Also, her bedroom is full of drawings of the butterfly and her voice is heard talking of butterflies throughout. During a climactic battle between Neville and a vampire Marley's voice can be heard saying "Remember the butterfly, daddy."

The butterfly is a powerful symbol of change, lightness and transformation. A butterfly changes from egg, to pupa or chrysalis and finally to the butterfly; Neville's character also has a similar transformation, in regards to his spirituality. Neville's purely scientific approach to life begins to change over the course of the movie, as Neville begins to have a more spiritual outlook to life. The butterfly symbol is most prominent near the very end of the movie where Neville fully understands his own personal destiny. A vampire or Darrkseeker smashes on a glass wall to get at Neville and a large butterfly is briefly shown to emphasize this message of transformation.

Throughout most of the film Neville is searching for a cure to the KV virus and it is through science that Neville believes that the answers can be found. However, it is only with the introduction of Anna (Alice Bragga) that Neville begins to understand his greater purpose in, "God's plan," or his own destiny.

The themes of spirituality and lightness come through in the soundtrack of the movie, as well. Bob Marley's songs like "3 Little Birds," and "Redemption Song" are played throughout and each song symbolizes man's destiny to make light of the darkness. Neville makes a speech about Bob Marley's life to Anna and highlights the importance of fighting concepts like hatred and racism. Neville states that, "Evil men (don't take) a day off so why should I?" All the while Neville relates his own story to Bob Marley's life.

This shows that man's destiny is to make light from the dark through humour, to search for meaning in the dark, or to create from the darkness. And this is what Neville does in his fight with the Darkseekers, by finding a greater meaning and a cure for the KV virus. This gives mankind, which has been decimated by the virus, a second chance.

The first half of "I Am Legend" is a commentary on the difficulty of surviving in complete isolation, without a community. Neville, who has been alone for three years, has coped by personifying elements in his environment. A dog is his best friend. As well, mannequins act as some sort of social support. This is similar to what Chuck does in "Cast Away." While stranded for four years on a deserted island Chuck befriends a volleyball, in order to maintain his sanity. Although, strange to people who are accustomed to everyday interaction it opens up the question, what would other people do in this situation? The clever addition of Wilson, by the writers of "Cast Away," allows for Chucks inner struggles to be heard, in the movie. Without the addition of Wilson much of the movie would be without dialogue.

Neville while being alone for three years has made the best of life by borrowing goods from the surrounding community. The use of a Mustang in the opening shots are a nice commercial placement and at the same time show the amount of freedom Neville has in a deserted city. The many paintings in Neville's apartment are from New York City's Museum of Modern Art, a permanent collection, and add personality to Neville's character.

Even with the many freedoms and luxuries available to Neville when he states "I'm halfway through the G's," at the video store, his loneliness again comes forth. It is also a subtle comedic highlight added by the writers. In later scenes it can be seen that Neville is borrowing and returning movies from the adult entertainment section of the movie store. To be halfway through the G's shows that Neville is coping with loneliness, by watching vast amounts of pornography.

As well, Neville's bonding with Sam and the mannequins at the video are other devices used by Neville to cope with the pains of loneliness. It is no surprise that after the loss of these personified objects later in the movie, that Neville has a complete emotional breakdown. It is this breakdown that leads to a possible suicide attempt at the hands of the Darkseekers, in a climactic scene.

Neville who experiences flashbacks and nightmares after the death of his family is struggling with a Jungian concept known as the personal unconscious. The personal unconscious holds all the unresolved grief and traumas, that are experienced during life. The fact that Neville relives these traumas through nightmares and flashbacks shows that his own personal unconscious is struggling to bring these emotions to the surface. Only with resolving with the grief of the past can Neville's character move onward.

When Neville enters the kitchen, after being rescued by Anna, the fact that he sees his wife and child first before seeing the reality of the situation, is an attempt by the personal unconscious, to bring into his conscious mind the grief and pain experienced, during the death of his family. Neville's own personal unconscious is reminding him that the grief and loss of his family has not been fully resolved and requires further examination. In the final moments of the film when Neville sacrifices himself, it is possible that the unresolved loss of his family is what drives Neville to succumb to the Darkseekers.
Many critics of "I Am Legend" have complained about the change of pacing in the movie and the different genres that the film attempts to fit into but these are devices that create for a larger target audience. It is usually the studio that pressures the writers, in this case Mark Protosevich and Akiva Goldsman, to reach a wider fan base and in turn this can water down the overall impact of a movie's message. This is only partially the case in "I Am Legend." The change of pacing in the movie brings the film to a satisfying climax. As well, the excitement that is missing during the first half of the movie is contrasted by the action in the second half. Also, the fact that "I Am Legend" fits into many genres diversifies its target audience and thereby ensures the likelihood of a more successful release. As in other cases the release of a Director's Cut on DVD is likely to stay more loyal to the director's vision rather than the studios.

In the end, "I Am Legend" uses subliminal imagery and symbolism to bring forth a spiritual message, which is important to the motivations of the characters. In addition, the theme of isolation and an individual's need for community, reflects on a need that is inherent in all of mankind. Both of these themes, along with others, are timeless and make for an enjoyable movie watching experience.