In Peril at End House, Charles Vyse is a cousin of Nick Buckley. He is Nick's cousin on her mother's side, and is her nearest living relation. In the event of Nick's death, he would inherit End House.
He is described as a "tall young man, rather pale, with impassive features. He is going a little bald at the temples, and wears glasses. His colouring is "fair and indeterminate".
Charles is a lawyer in the firm Vyse, Trevannion & Wynnard, and handles Nick's affairs for her, such as arranging the mortgage on End House, and asking her to let the lodge. He is also in love with Nick, but she does not return his affections.
Charles Vyse is played by Christopher Baines in the film adaptation of Peril at End House in Series 2 of ITV's Agatha Christie's Poirot drama series. The portrayal is faithful to the original. The full names of his partners as indicated on the nameplate outside his office are "James Trevannion" and "Henry Vynnard".
In the NHK anime adaptation The Mystery of End House, the details of Nick's will was changed. Here, Charles Vyse stood to inherit one third of her estate. Therefore Poirot, in investigating the various attempts to kill Nick, considered Charles Vyse one of three plausible suspects. The denouement in this adaptation is different. Here Charles did not need to read Nick's will. Poirot told the people gathered that the meeting was more of a wake for Nick. The voice actor behind the character of Vyse is not credited.