Sif is a fictional character appearing in comic books published by Marvel Comics, in particular those featuring Thor. Based on the mythological being of the same name, Sif first appeared in Journey Into Mystery #102. She is an Asgardian warrior and lover of Thor, who spends much of her time worrying about and searching for him, and often accompanies Thor into battle. She has also battled alongside Balder, who has developed an unrequited attraction to her, as she never shows affection for anyone but Thor and certain individuals who proved worthy to wield his hammer, Mjolnir, such as the noble alien warrior, Beta Ray Bill and the mortal Eric Masterson.

Sister of Heimdall, Sif has been the constant companion of Thor and Balder since childhood. Like most Asgardians, Sif was born with golden hair. Hers, however, was turned black after Loki jealously cut it and replaced it with enchanted hair made by dwarves. At an early age she showed great prowess as a warrior and was considered the best female warrior of all of Asgard, matched only by Brunnhilde. At one point she was given to the death goddess Hela by a giant in exchange for immortality, but Thor saved her by offering himself in her place. Hela was so impressed that she let them both go.

In Norse mythology, Sif is a goddess associated with earth. Sif is attested in the Poetic Edda, compiled in the 13th century from earlier traditional sources, and the Prose Edda, written in the 13th century by Snorri Sturluson, and in the poetry of skalds. In both the Poetic Edda and the Prose Edda, Sif is the wife of the god Thor and is known for her golden hair.

In the Prose Edda, Sif is named as the mother of the goddess Þrúðr by Thor and of Ullr with a father whose name is not recorded. The Prose Edda also recounts that Sif once had her hair shorn by Loki, and that Thor forced Loki to have a golden headpiece made for Sif, resulting in not only Sif's golden tresses but also five other objects for other gods.

Scholars have proposed that Sif's hair may represent fields of golden wheat, that she may be associated with fertility, family, wedlock and/or that she is connected to rowan, and that she may appear or be referenced in the Old English poem Beowulf.

The name Sif is the singular form of the plural Old Norse word sifjar. Sifjar only appears in singular form when referring to the goddess as a proper noun. Sifjar is cognate to the Old English sib (meaning "affinity, connection, by marriage") and in other Germanic languages: Gothic language sibbia, Old High German sibba, and German sippe. Sifjar appears not only in ancient poetry and records of law, but also in compounds (byggja sifjar means "to marry"). Using this etymology, scholar John Lindow gives the meanings "in-law-relationship", scholar Andy Orchard provides "relation", and scholar Rudolf Simek gives "relation by marriage".

Wonder Woman is a fictional character, a DC Comics superheroine created by William Moulton Marston. She first appeared in All Star Comics #8 (December 1941). The Wonder Woman title has been published by DC Comics almost continuously except for a brief hiatus in 1986.

Wonder Woman is a warrior Princess of the Amazons (based on the Amazons of Greek mythology) and was created by Marston, an American, as a "distinctly feminist role model whose mission was to bring the Amazon ideals of love, peace, and sexual equality to a world torn by the hatred of men." Known in her homeland as Diana of Themyscira, her powers include superhuman strength, flight (even though the original Wonder Woman did not have this ability), super-speed, super-stamina, and super-agility. She is highly proficient in hand-to-hand combat and in the art of tactical warfare. She also possesses animal-like cunning skills and a natural rapport with animals, which has been presented as an actual ability to communicate with the animal kingdom. She uses her Lasso of Truth, which forces those bound by it to tell the truth, a pair of indestructible bracelets, a tiara which serves as a projectile, and, in some stories, an invisible airplane.

Jane Foster Zlatovski (1912–1979) allegedly engaged, with her husband, George Zlatovski, in covert activities on behalf of the Soviet Union while employed in sensitive U.S. Government wartime agencies during World War II. They were indicted in 1957. Their case was never tried and both Zlatovskis denied the accusations.

Jane Foster grew up in San Francisco, California. Her father, Harry Emerson Foster, was the medical director of the Cutter Laboratories. Her mother was Eve Cody Foster. Foster attended Mills College in Oakland, California, graduating in 1935.

Foster married Dutch diplomat Alleendert Kamper in October 1936. She and Kamper separated after 18 months. Foster, required to spend five months on Dutch soil in order to finalize the divorce, travelled to Bali. She remained there until September 1939, returning to the United States due to the British declaration of war on Germany. She briefly joined the Communist Party in 1938.

Foster met and married Zlatovski in Washington, D.C. in 1943, then remarried him three years later. She was employed by the Board of Economic Warfare ond the Office of Strategic Services from late 1943 until early 1946 in the Indonesian section. Foster was one of the first OSS agents to reach Indonesia after the Japanese surrender in 1945, where she interviewed Sukarno to discover whether he planned to align himself with Allied interests. Foster wrote in her autobiography that Soviet agent Charles Flato was one of her closest friends at the Board.