And the deluge continues. With the 50th anniversary of her suicide approaching, two more biographers have plunged into the melee, assessing both Plath’s prodigious gifts and her dysfunctions.

Carl Rollyson’s “American Isis: The Life and Art of Sylvia Plath” has seemingly contradictory goals: to mythologize Plath as a latter-day Egyptian goddess and to strip away decades of encrusted lore by using primary sources to reveal the living woman. His Plath (who indeed compared herself to Isis) is wildly ambitious, “a genre breaker and cross-cultural heroine” who “would make herself and what she wrote both threatening and alluring, deadly and life-affirming.”

Overblown rhetoric aside, Rollyson, a Baruch College journalism professor and author of a Marilyn Monroe biography, has diligently combed the archives and interviewed Plath’s Smith College classmates and others who knew her. His workmanlike narrative gathers force when it reaches the inevitably fascinating marriage, which Rollyson compares to Monroe’s ill-fated union with playwright Arthur Miller.

It was not just Hughes’s infidelity with the beautiful Assia Wevill (who, in 1969, would also would take her life, and her daughter’s) that doomed the couple. Rollyson notes the tensions between Hughes’s need for privacy and Plath’s for acclaim; between her domesticity after their two children were born and his desire for freedom; between Ted’s sister Olwyn and Plath. “Much has been written about Plath’s mercurial moods,” Rollyson notes, but Hughes — no saint — “could turn from pliant to disdainful in a trice.”

Andrew Wilson’s “Mad Girl’s Love Song: Sylvia Plath and Life Before Ted” foregoes the gossipy pleasures of dissecting the marriage. But it is likely to become the definitive account of Plath’s early years. Before she met Hughes, Wilson writes, Plath “had gone out with literally hundreds of men,” some of whom inspired her pre-“Ariel” poetry and prose. Wilson has tracked down an astonishing number of them, from obscure figures who romanced her briefly to the hitherto elusive Richard Sassoon, with whom Plath was enamored when she met Hughes.

Born in 1932, Plath grew up in Winthrop and Wellesley, Mass., the daughter of Otto, a German-born entomologist who died when she was eight, and Aurelia, an English and German teacher with whom Plath had a close, conflicted relationship. Her father’s death had a profound effect on Plath and her poetry, and, Wilson speculates, may have intensified her need for male companionship.

Both biographers underline Plath’s precocity. A literary prodigy, she was first published at age 8, and magazines such as Seventeen, Mademoiselle (where she was a guest editor), and Harper’s accepted her poetry and prose before she had graduated from college. In recommendations for a Fulbright grant, her Smith College professors described her as the best student they had ever taught.

Wilson pinpoints Plath’s youthful obsessions, along with reading and writing, as money and sex. Plath, forced to economize, itemized her spending with obsessive rigor. At the same time, she struggled to contain a powerful sexual drive in a 1950s America that emphasized sexual repression, especially for women. “Being born a woman is my awful tragedy,” she wrote in her journal.

Plath was lovely, and Wilson makes clear how charming and charismatic she could be. But he paints her as a deeply troubled young woman whose 1953 suicide attempt, involving an overdose of sleeping pills, was no fluke.

What exactly was wrong with her? Wilson, though wary of definitive diagnosis, seems to believe that Plath was bipolar, subject to manic episodes as well as depression. He also endorses the suggestion of her longtime correspondent and friend Eddie Cohen that she suffered from borderline personality disorder.