Reverend Osborne Whitworth is a major character in Winstom Graham's Poldark novels and TV adaptations, serving as the secondary antagonist of the 1975 series (portrayed by Christopher Biggins) as well as the third and fourth seasons of the 2015 series (portrayed by Christian Brassington).
He is the hypocritical and loathsome vicar of Cornwall, whose public duty as a man of God is merely a facade for his truly perverse and abusive nature. Recently widowed, he appeals to George Warleggan for the hand of Morwenna Chynowyth (George's cousin-in-law and his stepson's governess) in marriage. Seeing it as an opportunity to gain influence within Whitworth's powerful family, George attempts to bargain a reasonable price, but consistently turns down Whitworth's outrageous offers. After some time, Whitworth informs George he is withdrawing his marriage proposal. However, soon after, Drake Carne (Morwenna's lover and the brother-in-law of series protagonist Ross Poldark) is arrested for "stealing" an expensive bible (which was actually a gift from George's stepson Geoffrey Charles). In return for Morwenna marrying Osborne, George drops all charges against Drake and has the former two married almost immediately.
Morwenna soon learns that, even near her stepdaughters, Osborne is abusive and overly demanding, regularly forcing himself upon her at night as part of his deluded belief in claiming what is his. Despite finally obtaining Morwenna as his wife, he allows himself to be seduced by her sister Rowella (who is really just doing so to keep his attention off of her sister). During Morwenna's childbirth, Osborne is warned by Dr. Enys that she may die, which he secretly hopes happens so that he may find a "suitable replacement". However, Morwenna lives and delivers him a son. He still insists on having relations with Morwenna and Rowella at the same time, until Rowella blackmails the Reverend by making him believe that he impregnated her while married to her sister, as well as Morwenna finally standing up to him, scaring him off (briefly).
While keeping his distance from Morwenna and continuing his affair with Rowella, Osborne's mother comes to town, hiring a governess to watch over his son. With Morwenna's threat removed, Osborne resumes his nonconsensual advances on her, repeatedly violating her each night. However, while having an affair with Rowella one night, her jealous husband spies on them snd later confronts him at night in the forest. During their brief scuffle, her husband knocks Osborne off his horse, trapping his foot in the strap as the horse runs off. The consistent injuries sustained kills Osborne, and his body is later found the next morning.
In all adaptations, he is regarded as a vile man, even by George.