Victoria Woodhull (with Nicole Kidman- Gene Hackman as Commodore Vanderbilt)
Madame C.J. Walker (with Queen Latifah)
Alexander the Great (a good one, preferably a miniseries)
Hermann Göring
Although I’m not a Deadhead, I’d like to see a biopic about the early days of the Grateful Dead.
Has anyone mentioned Alexander von Humboldt? That guy was amazing. From 1799 to 1804, he explored much of South America (and up into Mexico), making all kinds of discoveries, getting into all kinds of trouble, meeting all kinds of people, even climbing much of the way up a huge Andean mountain. If you read from his journal, you’ll see he had a sense of humor, too. Pure Hollywood, IMHO.
Explorers? How about Captain Cook – who crossed both the Arctic Circle and the Antarctic Circle and completed two full tours of the Pacific before, um, well, the third trip didn’t turn out quite as well.
Need a stunt double?
Yikes! DiCaprio? He was badly miscast as Howard Hughes; as Orson Welles he’d not only be way out of physical type but also vastly out of his league. The only actor I can think of off the top of my head who looks enough like Welles would be Jonathan Frakes, but he hasn’t the chops to handle the role.
I’d like to see Robert Oppenheimer portrayed; he was such a conflicted, contradictory individual that it would make an interesting study. I think Graham Greene’s life would make a fairly interesting story as well. And if you don’t mind obscure (from the veiwing public’s point of view) how about Srinivasa Ramanujan, the Indian mathematical prodigy. Of course the difficult bit about a biopic is presenting someone’s life as a coherent story in the timeframe of a film; since peoples’ lives are typically quite rambling and aimless, it’s hard to present more than a small slice of someone’s life in anything like a manner that is both interesting and accurate; witness Kinsey, which took substantial liberties and tried to create an overarching theme, making it a more easily consumed film but a less-than-accurate portrayal of the man.
Stranger
I’d like a period piece about the Harlem Renaissance of the 1920s that focussed on the politics, music, visual arts and literary heritage before the lights dimmed on sponsorships and patronage with the crash of '29 – the major biographical emphasis being on a wild array of period artists/activists like Marcus Garvey, Zora Neale Hurston, Madam CJ Walker, Countee Cullins, photographer James Van der Zee, and of course Langston Hughes.
I would do it as an arthouse film in which the main character is a young man who fears he’s schizophrenic because the ghost of Dick talks to him and tells him about his life. Then he reads something from Dick about a “ghost from the future” he talks to. Work in the whole trademark Dick “reality ain’t what you think it is or is it?” side.
Years ago Aaron (West Wing) Sorkin was going to film the life of TV inventor Philo Farnsworth, but he shows no signs of getting off the pot and the project is now undoubtedly optioned into oblivion.
Were that not the case, I would cast Willem Dafoe in the role of the hollow-cheeked, haunted genius wracked by depression, alcohol and corporate conspiracy. Possibly with Joan Allen as the Long-Suffering Wife™, and Bob Hoskins in the role of Phil’s arch-nemesis Gen. David Sarnoff.
I think the life stories of actresses Jean Harlow, Theda Bara, Anna Held and Kay Kendall would all make for terrific, huge, multimillion-dollar Hollywood projects.
Sure! You’re in western PA, and I’m in Cleveland, so we can arrange an audition whenever you’re ready. 
Agreed, but who on Earth could write an accurate yet dramatic script?
Genghis Khan
Jack Kerouac (just checked this, and apparently Francis Ford Coppola agrees with me)
Johnny and Luther Htoo
Rock Hudson
I’m a Civil War buff, so I’d love to see biopics of John Brown (of “John Brown’s Body” fame), Harriet Tubman, Gen. Stonewall Jackson, Denmark Vesey, Gen. Grant, and probably others I’m not thinking of now. Any of these people is interesting enough to sustain a good movie.
Dietrich Bonhoeffer.Theologian, Pastor, assassination plotter. Actually, I’d rather they didn’t do it, since I don’t trust Hollywood.
Ditto Billy Graham. If done right, and honestly, could surprise a lot of people.
There hasn’t been a great Churchill movie, and there should be.
In a much lighter vein: Moe Berg, Major League catcher, WWII spy, all-around odd duck.
I’d like to see one of Walt Disney, especially his earlier career (and setbacks), maybe ending with the first Mickey short, possibly going as far as “Snow White.”
Ooh, good one! Hughes himself would make a great film subject on his own – he did quite a bit of travelling when he was young.
I think it would be really interesting to see a biopic of James IV of Scotland, but that’s more likely to be a History Channel-style miniseries than an epic Braveheart-esque film. 
However, my favorite historical figure, Margaret of Anjou, definitely has a big-budget picture in her life story.
Chuck Berry
Henry Ford
John Frémont
Hong Xiuquan
Sam Houston
Lizzie Jennings
Jack Johnson
Robert Johnson
Charles “Lucky” Luciano
Elizabeth Packard
Charles Ponzi
Joe Pyne
Joseph Smith
Tecumseh
Paul von Lettow-Vorbeck
A miniseries based on Eleanor of Aquitaine could be great. She’s best known to modern offices from The Lion in Winter, but she had one hell of a life before she ever even married Henry II, let alone before she went to war with him. (Henry’s brother Geoffrey attempted to kidnap her on their wedding day.)
Sarah Bernhardt, who knew everybody of her times [and shagged quite a few of them] has never had a really good biopic (at least not in English, I haven’t seen any of the foreign films about her). Glenda Jackson was as close as they’ve managed and it wasn’t very memorable.
Houdini is long overdue for a good and accurate biopic (there have been miniseries and the Tony Perkins movie, but something really good with a very talented actor and a budget could be spectacular).
The kidnapping of Edgardo Mortara would be a good film, though I don’t think the Vatican would be too happy (unless Mel Gibson directed it, in which case Pius IX would be the hero).
A miniseries on the life of Herod the Great could also be really incredible. To me he’s the most fascinating well documented historical character in the New Testament even though he only makes a cameo. His disastrous love affair with his second wife (of an eventual ten) Mariamne would be the fulcrum, but his sister Salome (not the one who got head while dancing but her grandmother/great-grandmother/grandniece/great grandniece [the family was incredibly inbred]) was one of the great villainesses of ancient history (she could have given Graves’s Livia lessons in coldbloodedness), Cleopatra and Mark Antony had more than cameo roles in his life, the way he became king in the first place, his grandiose building and descent into paranoia, the intrigue that led him to kill three of his own sons (as well as many other relatives and his wife Mariamne’s entire family), all interesting.
A movie bio about Brigham Young’s divorce from Ann Eliza Webb (somewhere between his 19th and 54th wife, depending on the count) could be interesting as a TV job. I would not base it on Irving Wallace’s book about her (which I thought was shoddy scholarship), but on court documents and her own book. It was the big tabloid topic of his day because people were fascinated by the open practice of polygamy in general and Young (an old man at the time) in particular.
Or a movie depiction of the Vanderbilt Will lawsuits would be fascinating. I’ve mentioned it on the boards before, but- when Cornelius Vanderbilt (a veddy veddy bad man) died, he left an estate worth upwards of $100 million, this in 1877 when it’s almost impossible to translate that into today’s currency but suffice it to say he was the equivalent of a billionaire many times over (the richest man in America and on the short list of richest in the world). An abusive husband (at least to his first wife) and just general amoral person, he was obsessed with spiritualism late in life, and a womanizer throughout his life, and he became first a client and later a business partner and acolyte of the spiritualist sisters Victoria Woodhull and Tennessee Claflin, whose services he used to contact his dead first wife, mother, business enemies, and dead favorite son (killed in the Civil War), all of whom gave him the same message: leave everything to your son William Henry, the one you’ve never particularly liked. He did, dividing less than $2 million among his 8 daughters and younger son (still enough to make them very well to do by the standards of the day) and about $105 million to little sickly pasty middle aged William Henry.
It caused a huge lawsuit by the sisters and brother against William Henry and the transcripts are still a hoot. William Henry, shoved into the background for decades by a father who thought him a weakling, was feeding information that the old man (who was so terrified of evil spirits he had bowls of salt and voodoo talismans under his bed) thought only the dead would know to the spiritualist sisters, who of course were well compensated when he became the richest man in America (and died the richest man in the world 8 years later). But the case has it all: greed, sex, laissez faire of the most evil kind, ghosts (or something like them), Victorian America, etc…
Of course the gay voyeur part of me would love a movie biopic set in gay Hollywood- perhaps of William Haines or Rudolph Valentino (who some biographers believe was, though twice married, gay or bi- he was perty whatever he was).
furt, PBS recently broadcast a dramatic biographical film about Bonhoeffer, apparently German made. I haven’t seen it, so I can’t vouch for its quality.
To carp a little bit, I think most of the people listed here (at least the ones I’ve recognized) would be better served by a big fat biography rather than a biopic. Why? For the same reason that short stories and novellas tend to adapt better to the big screen than do 1000+ page epics. Movies generally aren’t long enough to encapsulate all of a big, epic, sprawling life. Either the filmmaker crams everything in and it feels rushed, or they focus on a few events and people complain about what was left out.
For that reason, I think people who were famous for one particular thing at one point in their lives would make better subjects. The Wright brothers, to pull from one of the first examples, would be good because the movie could focus just on their airplane experiments – screw Ohio, screw the bicycle shops.
Personally, I’d like to see a movie about Nat Turner’s slave rebellion. It’ll never get made because it would be seen as too racially incendiary, but it’s a good story – slavery, religion, vengeance, retribution, history, etc.