Some people’s lives are best told truthfully, others more loosely.

In one corner, we have Rocky, the iconic Best Picture-winning boxing movie starring Sylvester Stallone as the made-up Rocky Balboa. In the other corner, we have Chuck, an upcoming biopic starring Liev Schreiber as real-life boxer Chuck Wepner. The latter primarily depicts the 1975 bout between Wepner and Muhammad Ali, which inspired Stallone to write the script for Rocky. He’s since tried to downplay the connection, especially after being sued by Wepner, but it’s close enough to being a film a clef as any.

Chuck received mostly positive reviews when it played the big film festivals last fall, but it’s unlikely to become the phenomenon, let alone Oscar darling, that Rocky was. Its legacy surely won’t be as lasting, in part because true biopics don’t tend to get sequels. There are a lot of benefits to fictionalized accounts of real events and lives. For one thing, writers can play more with structure, chronology, themes, and other elements that make for a good film story. And nobody challenges their authenticity.

This is especially true for horror movies based on true stories. As scary as real life can be, it’s not always as frightening in moments as the genre’s conventions call for. We can look at the many movies inspired by the life and murders of serial killer Ed Gein to see how clever fiction can be with a single story. Even if the films Ed Gein and Ed Gein: The Butcher of Plainfield were better works in their own right, they wouldn’t have a chance against classics like Psycho, The Texas Chainsaw Massacre, and The Silence of the Lambs.

These days, filmmakers are stretching the truth with life rights, though, so instead of making something fantastical like Child’s Play, they can go ahead and use real names for something like Annabelle but also take liberties in the dramatization and narrativization of certain events (Child’s Play is inspired more by another story of a possessed doll, though I personally heard Ed and Lorraine Warren claim “Chucky” was also inspired by their experiences portrayed in Annabelle). It’s not documentary, after all…

Crime stories in general have always been fodder for fictionalization. Sometimes it’s clear but not too specific, as in the case of the original Scarface, loosely based on the life of Al Capone. The gangster’s later, more direct and faithful biopics, including 1959’s Al Capone and 1975’s Capone, aren’t as well-known or celebrated (but then, neither are many of the other fictional films inspired by Capone released around the same time as Scarface). Or Terrence Malick’s Badlands, which is the more famous and favored film version of the story of Charles Starkweather and Caril Ann Fugate than 2004’s Starkweather.

One example that is not so ambiguous with its subject is To Die For, in which Nicole Kidman plays a husband-murdering TV personality. Buck Henry’s script is adapted from a novel inspired by the case of Pamela Smart, who is portrayed by name by Helen Hunt in the earlier, more sensational TV movie Murder in New Hampshire: The Pamela Wojas Smart Story. Also Boogie Nights is obviously about a fictional version of porn star John Holmes, right down to a scene based on the Wonderland murders. Enough that the later Holmes biopic Wonderland often comes off like a remake of the Paul Thomas Anderson film.

For the most part, the fictional movies wind up better-known works. That’s true of the Jacques-Yves Cousteau-inspired Wes Anderson comedy The Life Aquatic with Steve Zissou compared to the new Cousteau biopic, The Odyssey, and will probably wind up the case with the Chet Baker-inspired 1960 film All the Fine Young Cannibals versus the recent Baker biopic Born to Be Blue. As evidenced by the popularity of To Die For, it’s not just a matter of the inspired takes’ tendency to come out before the real deal, either.

Occasionally, the opposite is true and the more authentic stories triumph. Bonnie and Clyde is a much more iconic picture than Fritz Lang’s 1937 film-noir You Only Live Once. Which is the better movie can be up for debate, of course, and the same is true of Dirty Harry versus Zodiac, the latter of which acknowledges the former in its telling of the story of the Zodiac Killer. They’re such different kinds of movies that comparison might be moot. Then there are the many fans of Boiler Room who still prefer its fictional take on the Jordan Belfort story to The Wolf of Wall Street. And many others choose Martin Scorsese film instead.

The reason those three more-directly based versions stand out is the same as why the more memorable fiction films typically do so in their match-ups. They depict the true stories with style, and maybe they aren’t concerned with every little detail being exactly as it happened. The makers of these movies wanted to deliver something enjoyable to audiences, not a fact sheet. So why bother with a movie so shackled to the truth? The “based on real events” stamp does attract, and it’s not usually employed without some kind of authorization.

For Chuck, it’s likely that its co-writer Jeff Feuerzeig, who previously helmed the Wepner documentary The Real Rocky, and referred to Rocky as a “hijacking” of his subject’s soul, might be set on getting the boxer’s life right rather than just entertaining. The new movie is definitely concerned with Wepner’s connection to Rocky, going even further than Zodiac in its address of its fictionalized counterpart, enough to play out as a response to it as much as, if not more than, a mere alternative.

It’ll be hard, therefore, to consider Chuck independently of Rocky. To say this is not just the definitive but only worthwhile depiction, since it rests so much on the other’s existence. But it’s possible to accept it as a better film, regardless, if it turns out to be that. We’ll see if Chuck can go the distance against Rocky’s crowd-pleasing version, if not knock it out, when it opens (following a stint at the Tribeca Film Festival) on May 5th. For now, check out the new trailer for the biopic below.