Namor, the Sub-Mariner
Namor is one of Marvel's earliest characters and one of its most powerful and ambiguous. Despite being THE first mutant and strongly associated with The Fantastic Four, Namor's film rights do not reside at Fox but at Universal Studios. A film has been in the works at Universal since 2004 when the studio hired David Self (Road to Perdition) to write a script and, at one point was on the slate for a 2007 release which would have been directed by Chris Columbus. Columbus pulled out of the project and was replaced by Jonathan Mostow (Terminator 3: Rise of the Machines, Surrogates) but obviously no progress was made. Despite the lack of movement towards a film in the past 5 years, the rights to Namor still reside at Universal as Kevin Feige reiterated this past summer.
While Iron Fist may be the most well-known martial artist on Marvel's roster, Shang-Chi is The Master of Kung Fu. A product of the 70s, a time when Kung Fu ruled the world, Shang-Chi has had a long tenure in the Marvel universe and is one of the best hand-to-hand combatants it has to offer. He has been a Hero for Hire and an Avenger and has been able, through his incredible martial arts skill, to defeat many super-powered villains in his time.
In 2001, Stephen Norrington (Blade, The League of Extraordinary Gentlemen) signed on to direct The Hands of Shang-Chi: Master of Kung Fu. The film went through various stages of development until 2006 when it was set to be directed by Yuen Woo-ping (Drunken Master) and produced by Ang Lee. As of 2006 it appears that the film rights are with Marvel which provides the opportunity that Shang-Chi appears when the Heroes for Hire hit Netflix in 2015-16.
Cloak and Dagger
Cloak and Dagger are teen mutants, or possibly mutates, who first appeared in the pages of Spider-Man. Cloak's powers allow him to absorb people into his cloak and teleport them to the Darkness Dimension. Dagger can create light daggers which she controls psionically and can drain the life force from humans. The two form a mutually symbiotic team as Dagger's light fills Cloak's chronic hunger for light and his constant absorption of her light prevents her from becoming dangerously over-charged.
Marvel began work on a Cloak and Dagger film in 2006, but recently have put more energy into developing the duo for a live-action TV series. The pair have appeared in other series such as The New Warriors and The Runaways and may be a part of a second round of series in the Marvel/Netflix deal if the first round goes well.
The Taskmaster is one of Marvel's B-list baddies but certainly a fan favorite. Gifted with the ability to recreate the physical movements of anyone he sees through a photographic memory, the Taskmaster is a dangerous foe capable of going toe-to-toe with any of the Marvel universes best hand-to-hand combatants. While he began his time as a villain and ran an academy to train up and coming villains such as Crossbones, most recently Taskmaster served as a Thunderbolt before becoming a Secret Avenger.
Joe Carnahan (The Grey, The A-Team) signed on to direct a solo Taskmaster film which would detail the origins of the character and revisit his infamous beating at the hands of Marvel's rooftop vigilante, Moon Knight. A Joe Carnahan directed CBM is on my list of things I'd love to see before I die and, given Carnahan's attachment to this and the short-lived 70s themed Daredevil film, it might be on his bucket list as well. The Taskmaster will, at some point, make his entrance into the MCU, possibly on Agents of S.H.I.E.L.D.
Deathlok is the name given to several dead humans reanimated as cyborgs throughout the Marvel continuity. These cyborgs have, at different times, worked for and against S.H.I.E.L.D. and various superheroes.
In 2004, Paramount Pictures hired Paul McGuigan (4 episodes of the BBC's Sherlock, Lucky Number Slevin) to direct a film based on a screenplay by David Self. With the very techie direction the MCU is headed in, it's not beyond hope that we could see Deathlok, or at least the Deathlok technology, incorporated into Agents of S.H.I.E.L.D. Perhaps one of the new agents appearing later on down the road might have an accident...
Of course there are several other films that have gone through various stages of development, Runaways most prominent among them, and certainly others about which we've never heard. While it's possible that some of these are dead project, it was fun to think about them anyway. You never know which director might take a stab at one of these or, perhaps, a completely different original project. It just takes the right confluence of events to get a great film!