Maurice Wilkins was a colleague of Franklin at King's College who, like her, was using X-Ray diffraction to try to crack the code of DNA. Through a communication mishap (the first of many, to be sure) Wilkins apparently misunderstood Franklin's role in the lab and thought that she was there as his assistant. This led to a frosty relationship between the two, and it was Wilkins who later went on to show Franklin's Photograph 51 to Watson and Crick without her permission. Whether this was a careless mistake or a spiteful move on Wilkins' part remains unclear, and while he might not be a villain of history, he certainly won't be a hero of Franklin's biopic. James McAvoy would be convincing in this scientist role, and even bring a brooding quality to the antagonist of Wilkins.
French scientist Jacques Mering taught Franklin the technique of X-Ray diffraction at the Laboratoire Central des Services Chimiques de l'Etat in Paris. Though their relationship was not central to Franklin's King's College years, it certainly played an important part in her scientific development, and eventually led her to taking the first clear photo of DNA's helix structure. We think that French actor Vincent Cassel would be well suited to this role.
Born in London in 1920, Rosalind Franklin wanted to be a scientist by the time she turned 15. She graduated from Cambridge in 1941 and went on to study at the Laboratoire Central des Services Chimiques de l'Etat in Paris, where she learned X-ray diffraction—the technique that would help her take Photograph 51—from crystallographer Jacques Mering. In 1951, while working at King's College London as a research associate, Franklin made the discovery that changed the world, but didn't substantially change her life. Franklin died of ovarian cancer just six years later. When the Nobel Prize was awarded to Watson, Crick, and Wilson in 1963, Franklin was not eligible to receive the award posthumously. We can see Emilia Clarke rendering Franklin as a stoic but passionate character, tapping into the internal, beneath-the-surface dilemma of her character as she does so well as Daenerys on Game of Thrones.
Together with Francis Crick, James Watson is often the first to come to mind when talking about the discovery of the double helix. While the Cambridge men were the first to draw definitive conclusions from Photograph 51, they undoubtedly owed a great debt of their success to Franklin's research, data, and technique. Yet in his 1968 memoir The Double Helix, Watson spoke disparagingly of Franklin, even referring to her as "Rosy," a nickname she never used. Eddie Redmayne is a Cambridge alum himself, and while he certainly possesses that slightly nerdy charm that the role calls for, it'd be interesting to see him take on the nasty, chauvinistic aspects of Watson's character.
Raymond Gosling was Franklin's student with whom she successfully rendered Photograph 51 and published an article. Today, Gosling is thought of along with Franklin as the uncredited fifth discoverer of the double helix. We think that Harry Potter alum Matthew Lewis could bring an inquisitive, studious charm to the role of Franklin's protégé.
Later in her life, Rosalind Franklin became close friends with Francis Crick, who, unlike his colleague Watson, did not publicly defame her. Irish actor Colin Morgan of BBC's Merlin could likely pull of this historical role, playing to both the competitive and intimate aspects of Crick's relationship with Franklin, as well as to the thrill of his part in the discovery of the double helix.