Zerelda Gray Sanders Wallace (August 6, 1817 – March 19, 1901) was the First Lady of Indiana from 1837 to 1840, and a temperance activist, women's suffrage leader, and inspirational speaker in the 1870s and 1880s. She was a charter member of Central Christian Church, the first Christian Church (Disciples of Christ) in Indianapolis, Indiana. Her husband was David Wallace, the sixth governor of Indiana; Lew Wallace, one of her stepsons, became an American Civil War general and author.

Zerelda Gray Sanders was born on August 7, 1817, in Millersburg, Kentucky. She was the eldest of five daughters born to John H., a physician, and Polly C. (Gray) Sanders. After receiving a grammar-school education, she attended a boarding school at Versailles, Kentucky, from 1828 to 1830. Around 1830 the Sanders family moved to Indianapolis, where her father continued his medical practice. Zerelda was an avid reader as a youth and had an interest in medicine.

On December 25, 1836, nineteen-year-old Zerelda married thirty-seven-year-old David Wallace. At the time he was the lieutenant governor of Indiana and a widower with three sons from his first marriage. Zerelda became a stepmother to Wallace's sons (William, Lew, and Edward). The couple also had six children of their own, but only three of them (Mary, Agnes, and David) survived to adulthood.

In 1837, a year after the Wallaces were married, David was elected the sixth governor of Indiana, He served from December 6, 1837, to December 9, 1840, and Zerelda, who was in her early twenties, became First Lady of Indiana. In 1841 David served a one-year term in the U.S. Congress, but failed to win re-election and returned to his Indianapolis law practice in 1842. He was judge of the court of common pleas for Marion County, Indiana, until his death in Indianapolis on September 4, 1859. After David's death, Zerelda was left nearly penniless with young children still at home, but she refused assistance from other family members. Fortunately, she retained the family's residence in Indianapolis and took in boarders to earn an income. In 1870 she took on the additional task of caring for the four children of her daughter, Mary, who had died in childbirth.

Lew Wallace, Zerelda's stepson, became an American Civil War general and author of the novel Ben-Hur: A Tale of the Christ. It is believed the character of Ben Hur's mother is modeled after Zerelda, who was a devoted mother to her children and stepsons. Zerelda was also a sister-in-law of Richard Jordan Gatling, inventor of the Gatling gun. Gatling married Zerelda's younger sister, Jemima Sanders.

Her daughter-in-law was an opera singer, Zelda Seguin Wallace, the wife of David Wallace Jr. Zelda Wallace performed at suffrage events hosted by Zerelda Wallace.

Zerelda, who was described as shy and without personal ambition, showed little interest in becoming active in public life before 1873. However, she was an active member of the first Christian Church (Disciples of Christ) in Indianapolis. She was a charter member of the congregation, and later served as a church deaconess. Organized in 1833, it was the "mother church" of the other Disciples of Christ congregations in Indianapolis, and was renamed Central Christian Church in 1879. In 1890 its congregation dedicated a new church at Fort Wayne Avenue and Walnut Street, where Wallace's funeral service was held in 1901.

By the 1880s Wallace was not hesitant to demonstrate her convictions on the issue of temperance. In 1883 she refused to take communion unless unfermented grape juice was substituted for wine. Central Christian Church became the first Disciples of Christ church in Indianapolis to switch to grape juice for its communion services; other Disciples of Christ congregations in the United States soon followed its lead.