Vera Elizabeth Claythorne is of the third class social status. She works with young children and teaches young girls to play tennis. She was also the last victim to die in the story.
Invitation
Young Vera Claythorne was invited by her new employer, Una Nancy Owen, to work as a secretary. She was found through the Skilled Women's Agency with their recommendation.
Crime
On the 11th day of August 1935, she supposedly killed the young Cyril Ogivile Hamilton, a child under her care. Whenever asked she insists that it wasn't her fault and that even Cyril's mother did not blame her for what happened. As the story progresses, however, it is revealed Claythorne hated and did intentionally plan to kill the boy but in a way that made it look as though Cyril disobeyed her and that she was the hero who had tried to rescue him.
Claythorne's motives were greed, money and love!
Vera's boyfriend Hugo was Cyril's uncle and original heir to his family'all fortune, which changed upon Cyril's birth, leaving Hugo penniless. After careful planning and manipulation Vera's plan succeeded and Cyril drowned whilst trying to swim out to a large rock.
An enquiry followed Cyril's death after which Vera was thanked by a devestated Mrs Hamilton for trying to save her son. Moments later Vera was confronted by Hugo. Whilst everyone else believed her story, Hugo had somehow figured out what she had done and was angry that Claythorne made young Cyril, whom Hugo loved very much, drown for her own ambitions.
Vera insisted that he was mistaken, insisting that she loved both Hugo and Cyril but unfortunately for her Hugo didn't buy a word of it. He immediately broke up with her, after which he disappeared out of her life. Nevertheless, Vera remained very much attached to him, despite Hugo's warning that if he ever found proof of what she had done, he would make sure she was sent to the gallows.
Island Events
Vera Claythorne is down-to-earth and calm during most of the story, except for one breakdown where she was talking about the nursery rhyme and its coincidences with the murders. One night, whilst going to take a bath she walks into her room, lights off, only to be disturbed by seaweed hung from her ceiling.
She screams giving the killer a chance to "kill" Wargrave.
Death
Vera is the last victim, and second to last person to die on the island (the final person being the killer themselves) and like the last verse of the rhyme states, she hangs herself. She does this because she had just shot Lombard and is starting to feel all the guilt she's been holding onto for years and the traumatic events on Soldier Island causing her to feel post-traumatic stress. Also, the murderer had set up her environment to encourage her to hang herself.
Films & TV series
The vast majority of Vera's character is kept consistent in the films to her novel counterpart. However the ending varies. In the 1940s movie, she pretends to shoot Lombard (revealed to be Charles Morley) to fool the murderer. Like the novel, the killer is the same, but Vera does not hang herself as her literary counterpart does. She is able to see for herself who the killer is and watches him die with Morley at her side.
In the 2015 edition, once "everyone else" is dead, Vera enters her room to find the environment set up and prepares to hang herself, only to be confronted by the killer, Justice Wargrave. Shocked to discover who was behind these terrible events, Vera loses her balance succeeding in trapping but not successfully hanging herself. As she struggles for dear life to free herself, Judge Wargrave provides his confession and an explanation as to the reason behind the events. As he gloats triumphantly about the perfectness of his crime, and how he himself will soon die in an unfathomable way, Vera notices a chink in his armour, and tries to exploit it. Pointing out that there are no bullets left for the judge to kill himself with, Vera offers to make a deal with Wargrave: in exchange for her life, she will pin it all on Philip Lombard. She say's that she will tell (and convince) everyone that she killed him in self-defence. She insists that she can do it, after all - she did it once before!
Her plea however, falls on deaf ears as Wargrave (after letting her dwell on that faint glimmer of hope) yanks the chair Vera was balancing on for support out from under her, causing her to start choking in earnest. As he leaves Wargrave reveals that there is in fact one last bullet left, "[Vera] forgot the one that shot [him]". He then closes the door on her, and leaves Vera to her fate dying shortly afterwards by his own hand.