Nani Alapai (December 1, 1874 – October 1, 1928) was a Hawaiian soprano singer during the early 1900s. Despite not receiving any formal musical training, she was hired as a vocalist of the Royal Hawaiian Band by bandmaster Henri Berger. She became the leading prima donna of the early era of Hawaiian music through her traveling performances with the Royal Hawaiian Band in Hawaii and on the mainland United States. Recording a number of songs, she helped popularize "Aloha ʻOe" by Queen Liliʻuokalani with one of the earliest recordings of the song. She directly and indirectly influenced many later Hawaiian musicians including Lena Machado and her adoptive grandson Kahauanu Lake.

Julita Nani Malina was born in Līhuʻe, on the island of Kauaʻi, on December 1, 1874. Her parents were Keokilele Halemanu Punana Ukeke (died 1913), a Native Hawaiian from Wainiha, and John Malina Sr, an early Filipino settler in Hawaii. Her father worked as a paniolo (cowboy) at Kipu Ranch, owned by William Hyde Rice, and received his surname from the Hawaiian pronunciation of Manila. The family surname has sometimes been spelled Molina. She had many siblings while growing up including five brothers and eight sisters. She received her education at a Roman Catholic boarding school for girls in Honolulu.

Around 1895, she married William J. Alapai and became known as Mrs. or Madame Alapai. On November 20, 1910, after the death of her first husband, she remarried to W. C. Luke and became known as Madame Alapai Luke. For an unknown reason, her marriage certificate listed her parents as Panakiko Kealii and Anna. Alapai and Luke were divorced by 1916, with her citing non-support in the court case.

She adopted and raised Cecelia Kuliaikanuʻuwaiʻaleʻale Waipa (1907–1981), granddaughter of former Hawaiian Royal Guard Captain Robert Parker Waipa—a member of the extended Parker ranching family of the island of Hawaii. Cecelia's first marriage was to Thomas C. Lake and she later married Prince David Kalākaua Kawānanakoa. A musical entertainer herself, Cecelia was the mother of Hawaiian musician and composer Kahauanu Lake, who received the Hawai'i Academy of Recording Arts Lifetime Achievement Award in 1989, and was inducted into the Hawaiian Music Hall of Fame in 2004.

Alapai received no formal musical training, but learned how to sing by entertaining audiences. There is disagreement about her tenure with the Royal Hawaiian Band. Based on her 1906 biography printed in the Hawaiian language newspaper Ka Nupepa Kuokoa, she joined the band around 1897 (nine years before the publication of the biography). At the time, Henri Berger was bandmaster and hired her to sing with the Band as a female soprano soloist. Later erroneous sources, including the personal interviews of Kahauanu Lake, and articles written in the Haʻilono Mele newsletters of the 1970s, claimed she was the band's first female vocalist, debuting with them in 1873, singing with the band for 40 or 43 years. However, census records taken during her second marriage show that she was not even born in 1873.

She accompanied the band on many of their 1905 appearances in the continental United States. Contemporary newspaper accounts describe how her voice enchanted the people of Portland, Oregon. When she sang there with the Band, the Oregon Daily Journal noted, "Her voice is naturally sweet and her talent distinctively native. She is ambitious for operatic work, and there is just a prospect that she may lead a native opera company in Honolulu within a short time."

During her career, she became known as the Prima Donna or Kāhuli of the Royal Hawaiian Band. The latter is a reference to the Oʻahu tree snails (Kāhuli in Hawaiian) which according to Hawaiian folklore are able to vocalize and sing sweet songs. Visiting the islands in 1907, Charmian London and her husband, American writer Jack London, heard her sing during a luau. Charmian noted:

She sang for us without reserve, out of her very good repertory. Her voice is remarkable, and I never heard another of its kind, for it is more like a stringed instrument than anything I can think of—metallic, but sweetly so, pure and true as a lark's, with falls and slurs that are indescribably musical and human. The love-eyed men and women lounging about her with their guitars and ukuleles, garlanded with drooping roses and carnations and ginger, were commendably vain of showing off their first singer in the land, and thrummed their loveliest to her every song. No one can touch strings as do these people. Their fingers bestow caresses to which wood and steel and cord become sentient and tremblingly responsive.