Constantine was written using some elements from Garth Ennis’ "Dangerous Habits" story arc and others—such as the inclusion of Papa Midnite—from the Original Sins trade paperback.

However, the film changed several aspects of the source material, including a number of cosmetic changes to the lead character’s appearance: Reeves played the role with his natural accent and hair colour whilst the original character was intentionally drawn to resemble English musician Sting and originally came from Liverpool.

The film was also set in Los Angeles, with the director pointing out that the comic book was not exclusively set in London either.

Other differences to the character were made, such as giving him the psychic ability to see "half-breeds" as they truly are.

That ability, in the film, is what caused him to attempt suicide and which led to his damnation rather than his role in summoning a demon that killed a young girl.

The resolution of the lung cancer plotline in the film was also amended, with Lucifer saving the redeemed Constantine to give him a second chance at falling rather than being tricked into doing so as was seen in the comic book.

Scenes with actress Michelle Monaghan as Constantine's lover, a half-breed demon named Ellie based on the succubus Ellie in the Hellblazer comics, were cut from the movie to make Constantine more of a lonely character.

Constantine was a financial success, grossing $230,884,728 in worldwide gross sales.

To tie into the films release, a novelization by John Shirley and a video game adaption of the film was also produced. Warner Home Video announced that the film was to be released on HD DVD on March 28, 2006.

It would be one of the earliest titles to be released on that media format.

However, following delays to the launch of the HD DVD format, Constantine eventually made its debut on HD DVD on June 6, 2006. Warner Home Video released a Blu-ray Disc version of the film on October 14, 2008.

Constantine was met by critics with mixed reviews. At the review aggregation site Rotten Tomatoes, the film holds a normalized rating of 46% based on the reviews of 214 critics with an average rating of 5.5/10.

At Metacritic, an aggregation site which assigns a weighted average, the film holds a rating of 50 out of 100 based on the reviews of 41 critics.

Richard Corliss of Time magazine praised the film calling it "a one-of-a-kind hybrid: a theological noir action film".

In crediting the actors, he specifically cited Keanu Reeves' ability to "retain his charisma in a weird-silly moment" in addition to the performances of Tilda Swinton whom he referred to as "immaculately decadent".

He also praised Francis Lawrence's usage of a significant number of camera locations and angles. He was, however, critical of the movie's climax, referring to it as "irrevocably goofy".

Ella Taylor of L.A. Weekly gave the film positive feedback, stating, "Constantine, which opts in the end for what I can only describe as a kind of supernatural humanism, is not without its spiritual satisfactions.".

Carina Chocano of the Los Angeles Times wrote, "Keanu Reeves has no peer when it comes to playing these sort of messianic roles—he infuses them with a Zen blankness and serenity that somehow gets him through even the unlikeliest scenes with a quiet, unassuming dignity."

Pete Vonder Haar of Film Threat gave the film three stars out of five, stating that "the film barely succeeds, thanks to impressive visuals, the idea of an uncaring God wagering with Satan for souls, and two immensely enjoyable scenes in which Reeves actually plays his character as the cynical asshole he really is."

Jack Matthews of the New York Daily News gave the film a 2.5 out of 5, stating, "For all its spiritual angst, Constantine is about as silly as fantasies get."

Michael Sragow of The Baltimore Sun also gave the film a 2.5 out of 5, stating, "It all comes off as a case of filmmakers wanting to have their communion wafer and eat it, too."

Desson Thomson, a writer for The Washington Post, had similar sentiments of the film, specifically panning the film's distancing from the series of graphic novels upon which it is based:

If you are a fan of the "Hellblazer" comic book series, on which this movie is based, you'll definitely need a distraction.

The relation between Constantine and its source material is, at best, superfluous. The disparity starts with the original John Constantine) being from Liverpool, England. Reeves from the city of John and Paul? As if.

Resources: imdb.com,
Wikipedia.org

Constantine - 2005

Set in Los Angeles, California, John Constantine (Keanu Reeves), a chain-smoking cynic, has the ability to see half-angels and half-demons true forms. He seeks salvation from eternal damnation to hell for a suicide attempt in his youth, by sending half-demons back to Hell with his sidekick Chas (Shia LaBeouf). However, full demons have begun attempting to cross over.

Disturbed by this information and with his death looming over him due to lung cancer, Constantine seeks an audience with the androgynous half-breed angel Gabriel (Tilda Swinton). Gabriel tells him that as he does his exorcisms to escape Hell and for his own benefit, they are vain acts that wont spare him.

Departing, he encounters LAPD officer Angela Dodson (Rachel Weisz), investigating the death of her twin sister Isabel, who leapt from the roof of the mental hospital she was committed to. Constantine is attacked by a true demon, but kills it. Upon attempting to speak with Papa Midnite (Djimon Honsou) about this attack, he is rebuffed and dismissed.

Papa Midnite is a former witch-doctor turned owner of a nightclub that serves as neutral ground for half-breeds. Constantine, with the help of his associates Beeman (Max Baker), Hennessy (Pruitt Taylor Vince), and Chas, begins investigating the situation. Constantine tells Angela that God and Satan have a standing wager for the souls of all mankind.

The rule for this wager is that angels and demons cannot manifest on Earth (however, half-breeds can), but can possess and influence humans. Afterwards, Constantine finds out Isabel was psychic, and her visions lead to her institutionalization. With the help of Hennessy and Beeman, Constantine finds out that the demons are working for Mammon, Satans son.

Mammon wishes to create his own kingdom on Earth. In order for Mammon to come to Earth, he needs divine assistance and a powerful psychic, for which reason half-demon Balthazar (Gavin Rossdale) locates Isabel and Angela. Angela reveals that she possessed the same gift but denied hers to the point that it became inactive.

At her request, Constantine reawakens it so she can see demons and angels true forms. Constantine attacks and interrogates Balthazar, who reveals that Mammon has obtained the Spear of Destiny, which has the blood of Jesus Christ encrusted on it. Angela is kidnapped to be used as the portal for Mammons entrance to Earth.

Constantine storms Midnites club and after a brief scuffle, Midnite allows Constantine access to the chair, an old electric chair from Sing Sing Prison that had killed over 200 people. It grants Constantine visions which show him that the Spear was discovered in Mexico and that it is already in L.A. Constantine and Chas go to Isabels hospital.

Mammon is conducting the ritual to rise in Angelas body. After exorcising numerous half-breed demons, the pair interrupt the ritual and attempt to exorcise Mammon from Angela, costing Chas his life at the hands of an invisible party. Using sigils on his arms, John forces the party, Gabriel, to reveal itself, but Constantine is promptly subdued.

Gabriel resents Gods favoritism towards humanity, and the forgiveness they are readily given. Gabriel believes that by bringing Hell to Earth, humans can become worthy of Gods love through repentance and faith. Gabriel throws Constantine from the room and begins to release Mammon. As Gabriel goes to stab Angela with the Spear and release Mammon, Constantine slits his wrists.

Time stops and Lucifer (Peter Stormare), who hates Constantine enough to collect his soul personally, arrives. Constantine tells Lucifer about Mammons plan and Lucifer sends Mammon back to Hell to keep Mammon from conquering Earth before him. Gabriel attempts to smite Lucifer, but is relieved of its holy powers and defeated.

In return for helping Lucifer, Constantine is owed a favour, but rather than asking for an 'extension' and be restored to life, he instead asks that Isabel be allowed to go to Heaven. Lucifer happily obliges, but, as he begins to drag Constantine to Hell, Heaven appears before him.

By sacrificing himself for Isabel when there was clearly nothing in it for him, Constantine has proven himself worthy to enter Heaven. Infuriated, Lucifer heals Constantines wounds and cures him of his cancer so that Constantine would have a second chance to 'prove that he truly belongs in Hell'.

Constantine retrieves the Spear and departs with Angela, but not before a now-human Gabriel attempts to goad Constantine into committing murder, only for Constantine to simply respond to his efforts by punching him to introduce Gabriel to pain.

Constantine then gives the Spear to Angela and instructs her to hide it where no one can find it. The final shot before the credits reveals that Constantine has switched from cigarettes to gum. After the credits, Constantine visits Chas grave and sees Chas rise into Heaven as an angel.