In any story, a dynamic character usually experiences a change of some sort, whether it is a change in personality, character, lifestyle. On the other hand, static characters tend to display consistent characteristics throughout a novel.
In Agatha Christie's And Then There Were None, Judge Wargrave is a static character. A dynamic and shrewd, former judge, Wargrave is obsessed with the idea of true justice. He is fixated on committing the perfect murder and prides himself for being a 'hanging judge,' the kind who rewards evil with supreme justice. In the story, he is cold, analytical, and decisive; on the island, he becomes the natural leader for the group of hapless holiday-makers. Ironically, the same ability for dispassionate analysis and impressive emotional control also renders him the perfect murderer. No one suspects that he is the killer.
From the beginning of the novel to the end, Judge Wargrave remains the same homicidal megalomaniac who derives great pleasure in perpetuating his brand of justice on others and basking in the accomplishment of his macabre tasks. Wargrave views murder as the ultimate weapon against thwarted justice. From a very young age, he has reveled in the 'inexorable diminishment-the sense of inexorability' in the rhyme concerning ten, little Indian boys. To Wargrave, the perfect crime is one which promotes justice; it is art of the highest order, and he holds this view from the beginning of the novel to the end.
Along with Justice Wargrave, Emily Brent is also another static character. Described as 'Enveloped in an aura of righteousness and unyielding principles,' Emily demonstrates hypocritical religiosity from the beginning of the novel until her subsequent death. In the story, Emily is guilty of turning out her servant, Beatrice Taylor, at the moment of her greatest need. Pregnant and without prospects, the desperate Beatrice throws herself into the river. Far from sorry for her callous ways, Emily even condemns Beatrice for committing a double sin, that of illegitimate pregnancy and suicide. Emily dies of chloral hydrate and cyanide poisoning, oblivious to the fact that Wargrave's own brand of justice has been exacted on her.
A dynamic character in the story would be Vera Claythorne. Vera is on the island because she is guilty of deliberately letting her charge drown so that her lover can inherit an estate. Despite having been acquitted by the Coroner, Vera knows that she is guilty of murder. Her lover, Hugo, also knows this and will have nothing more to do with her because of her cruel sacrifice of an innocent boy's life. In the story, Vera's initial reserve and self-control falls apart as she sees her fellow guests die, one after the other. After Philip Lombard (another dynamic character), Vera is the last to die on the island. Wargrave's psychological maneuvers build on her nervous tension, causing the woman to lose the last vestiges of her control and to commit suicide by hanging.
Both Vera and Philip are initially presented as characters who can hold their own, 'in love or war,' but as the murders continue, the paranoia which besets them causes both to act in an uncharacteristic fashion. Philip, uncompromisingly callous, tells Vera that he feels no pity for her plight, despite the fact that she is a woman. However, the worldly-wise, former soldier strangely ignores his ability for shrewd assessment and falls prey to his personal prejudices about feminine frailty. AS a result of his miscalculation, he dies at Vera's hands. After she shoots Philip, Vera hangs herself. Instead of waiting to die, Vera administers what she thinks is her own brand of judgment on herself for letting Cyril Hamilton drown. While there are varying characteristics, the rest of the other ten guests on the island also display dynamic changes in attitude and manner as the story progresses. Please refer to eNotes excellent summary of the story!