Harold Pinter, the fiercely political Nobel Prize-winning British playwright who used suspenseful plots, odd halting dialogue, and working-class settings full of menace to create puzzling yet riveting drama, died Wednesday of cancer in London at the age of 78.

His second wife, the biographer and historian Lady Antonia Fraser, made the announcement today.

For most devotees of serious theater, Mr. Pinter stood as the great British playwright of his generation. That stature more or less endured though he came up in English theater with such sterling talents as John Osborne and John Arden, and ended up eclipsed by the slightly younger Tom Stoppard, who kept pounding out first-class plays while Mr. Pinter's reputation suffered from a move to A-list screenwriting and somewhat hysteric anti-Americanism.

For all that, "Pinteresque" - an adjective that came to describe clipped, down-to-earth dialogue, packed with disturbing pauses, whose meaning remains just beyond the audience's grasp - seems certain to remain a theatrical term-of-art.

Mr. Pinter was born in the East End of London on Oct. 10, 1930, the son of Jewish parents: Jack Pinter, a tailor, and his wife, Frances, a homemaker. After two terms at the Royal Academy of Dramatic Art, he dropped out and began his career as an actor, doing a BBC radio play, touring in Shakespeare, and working in provincial repertory theater.

His first play, The Room, received its initial production in 1957 from the Bristol University drama department, drawing praise from Harold Hobson, the influential Sunday Times drama critic whose support proved crucial in Pinter's career.

When Mr. Pinter followed that offering in 1958 with The Birthday Party, about a solitary guest at a seaside boarding house who is threatened by mysterious antagonists, the production lasted only six days and triggered reviews in national papers that described it as "half-gibberish" and a "baffling mixture" (One began, "Sorry, Mr. Pinter, you're just not funny enough").

Hobson, though, countered by crediting Mr. Pinter with "the most original, disturbing and arresting talent in theatrical London."

From the beginning, Mr. Pinter's work attracted such mixed responses, but subsequent plays such as The Dumb Waiter, The Caretaker and The Homecoming solidified Pinter's standing. As his signature style of artful pauses and provocative silences grew on playgoers - he once defended the device by declaring, "[B]elow the word spoken is the thing known and unspoken" - his reputation, aided by such American champions as New York Times drama critic Mel Gussow, settled into that of a modernist master.

He eventually wrote 32 plays, a novel, The Dwarfs, and 22 screenplays. As a screenwriter, Mr. Pinter specialized in adapations from novels, among them L.P. Hartley's The Go-Between and John Fowles' The French Lieutenant's Woman.

Nonetheless, some noted theater critics, such as John Simon, continued to protest that Mr. Pinter amounted to a "third-rate imitator of Beckett." Simon took that approach in reviewing Betrayal, about a wife's seven-year affair with her husband's best friend. In it, Mr. Pinter utilized a hoary literary device as old as Anatole France's Le Jardin d'Epicure in the 19th century and up-to-the-minute as the new film adaptation of F. Scott Fitzgerald's The Curious Case of Benjamin Button - the plot that somehow moves back in time.

"With Betrayal," hissed Simon, "Harold Pinter has committed the strategic error of writing a comprehensible play." Never before, argued Simon, had Mr. Pinter "deviated into sense, and thus into that manifest triviality, if not vacuity, that the percipient few had unfailingly noted, drowned out though their dissenting was by the din of hosannas."

Dissents they remained, however, as Mr. Pinter continued to pick up prizes throughout his career, including the Nobel in 2005. On that occasion, the Swedish Academy cited him for drama that emerges from the "hide-and-seek of interlocution."

Among Mr. Pinter's many other awards was, in 2004, the Wilfred Owen Prize for his poetry condemning U.S. intervention in Iraq. Way back in 1966, he was made a Commander of the British Empire. He also won the David Cohen British Literature Prize (1995), and Laurence Olivier Award for lifetime achievement in the theater (1996).

Although some observers regretted the strident anti-Americanism of Pinter's later years - in his Nobel Lecture, he called the crimes of the United States "systematic, constant, vicious, remorseless" - Mr. Pinter was aggressively political and activist from the beginning, if not overtly so in his earlier plays.

As far back as 1949, he refused to do his national service in Britain and was fined. In the 1980s, he formed the June 20th Society, a discussion group of left-wing writers and intellectuals such as Ian McEwan, Germaine Greer and Lady Fraser.

In his personal life, Mr. Pinter married the actress Vivien Merchant in 1956 and they had a son, Daniel, in 1958. The marriage ended in 1980. That same year, he married Fraser.

The elusive meaning of Mr. Pinter's plays - which became both a cliche among knowledgeable theatergoers and a kind of cachet attached to his work - struck not just playgoers but performers, such as the great English actor Sir John Gielgud. Gielgud's thoughts on the subject may well capture the way posterity will judge Mr. Pinter.

In his memoir, An Actor and His Time, Gielgud wrote about his great success in Mr. Pinter's No Man's Land: "[L]ots of people came round after every performance, both in London and America, complaining that they did not understand the play. 'What does it mean?' they would ask."

Gielgud's reply? "Why should the play 'mean' anything if the audience was held the whole time and was never bored? That is surely the important thing. . . it was enough for me that the audience was fascinated and mystified."

Contact book critic Carlin Romano at 215-854-5615 or cromano@phillynews.com.