The marriage to Burton may have unsettled her, showing her how simple her own dramatic taste was. Once a presence, she became an actress. Not a bad actress, but one unable to regain the shallow clarity of “Butterfield 8.” In the event, she reduced the brittle respectability in Burton to her level — that of boasting of diamonds. Martha in “Virginia Woolf” was an “ugly” woman, something the Taylor of the 1950s would never have been allowed to take on, and a part fundamentally offensive to her view of herself. Later, she tried to look like her former self, as witness the neurotic wealth of costume in “Divorce His, Divorce Hers” (73, Waris Hussein), the TV film released ghoulishly as she and Burton broke up. She was evacuated to America during the war and made her debut in “There’s One Born Every Minute” (42, Harold Young) before finding her place at MGM as a rapturous face in a collie’s mane: “Lassie Come Home” (43, Fred M. Wilcox). In her next film, “Jane Eyre” (44, Robert Steven- son), she was like a young Lizzie Siddall as the child who dies. She was a child still in “The White Cliffs of Dover” (44, Clarence Brown), a big hit in “National Velvet” (44, Brown), and “Life with Father” (47, Michael Curtiz). Her teenage period was happily brief: “A Date with Judy” (48, Richard Thorpe); “Julia Misbehaves” (48, Jack Conway); “Little Women” (49, Mervyn Le Roy); “Conspirator” (49, Victor Saville); and “The Big Hangover” (50, Norman Krasna).

It was Vincente Minnelli and the parental guidance of Spencer Tracy and Joan Bennett that ushered in her maturity in “Father of the Bride” (50) and “Father’s Little Dividend” (51). But her first really striking part was away from MGM as the rich girl in love with Montgomery Clift in “A Place in the Sun” (51, Stevens). That film not only established her own black-haired beauty, but set a popular standard for a decade. In the fifty years since, has any movie actress been so blatant about extraordinary beauty? Julia Roberts in “Pretty Woman” is the only case that I can think of. It also showed how unlucky she was to be the property of MGM, still dealing in Thalberg’s innocuous glamour. In the next few years she was wasted on insubstantial romances and genteel adventure pictures: indeed, her Rebecca in “Ivanhoe” (52, Thorpe) had something of the splendor of the silent screen. Otherwise she tended to sigh and dilate her violet eyes: “Love Is Better Than Ever” (51, Stanley Donen); “The Girl Who Had Everything” (53, Thorpe); “Rhapsody” (54, Charles Vidor); replacing Vivien Leigh in “Elephant Walk” (54, William Dieterle); “Beau Brummel” (54, Curtis Bernhardt); and “The Last Time I Saw Paris” (54, Brooks). But “Giant” was an improvement and signaled a special responsiveness to the naturalistic care of George Stevens. As if to prove her aptitude for saga romance, she was as atmospheric as a fading camellia in “Raintree County” (57, Edward Dmytryk), as a Southern girl who goes mad with love. These were her best years, leading to the Oscar for “Butterfield 8″ and the brimming explicitness of her beach bait for young men in “Suddenly, Last Summer” (59, Mankiewicz).

After “Cleopatra,” she clung to Burton to prove fidelity and professionalism: The “VIPs” (63, Anthony Asquith); the risible “The Sandpiper” (65, Minnelli); “The Taming of the Shrew” (67, Franco Zeffirelli); as Helen of Troy in “Doctor Faustus” (67, Neville Coghill and Burton); “The Comedians” (67, Peter Glenville); “Boom!” (68, Joseph Losey); and “Hammersmith Is Out” (72, Peter Ustinov). She was much more deeply stirred in “Secret Ceremony” (68, Losey), where she seems to catch the sense of sexual instability, and in “Reflections in a Golden Eye” (67, John Huston). But she was restored to former melodrama in “The Only Game in Town” (69, Stevens), “Zee & Co” (71, Brian G. Hutton), “Night Watch” (73, Hutton), and “Ash Wednesday”(73, Larry Peerce), shameless movies, but enough to reprise her brooding self-belief. She rediscovered dignity in “A Little Night Music” (78, Harold Prince). Fifteen years later, the update could list the continuing marital career — but no one cares now. It should mention “The Mirror Crack’d” (80, Guy Hamilton) and “Young Toscanini” (88, Zeffirelli) in theatres, as well as several TV movies: “Between Friends” (83, Lou Antonio); a juicy Louella Parsons in “Malice in Wonderland” (85, Gus Trikonis); as a star who comes out of a mental hospital to make a comeback in “There Must Be a Pony” (86, Joseph Sargent); running a Western brothel in “Poker Alice” (87, Arthur Allan Seidelman); and with Mark Harmon in “Sweet Bird of Youth” (89, Nicolas Roeg).

Yet the work of which she is probably most proud is her feisty, eloquent, and quite implacable resolve to have people talk and know about AIDS. It is somehow fitting that her astonishing strength and durability should now be given so generously to the vulnerable, and in 1993 she received the Jean Hersholt Humanitarian Award for this service.

Over the years, there have been jokes about Elizabeth Taylor — more than that, she was for a decade or so a roaring comedy of disaster. Yet at the tender age of seventy, she is one of those stars whose mere look or voice brings back so many memories. Her worthless movies of the seventies and eighties are not really held against her. It is to be hoped that she may yet give us a few sensational old ladies — something better than her role in “The Flintstones” (94, Brian Levant).

Nothing yet, except for “These Old Broads” (01, Matthew Diamond).

Excerpted from “The New Biographical Dictionary of Film” by David Thomson Copyright © 2010 by David Thomson. Excerpted by permission of Knopf, a division of Random House, Inc. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.