Louis Maurice Kasriel (1815, Provinz Posen, Kingdom of Prussia, now Krotoszyn, Poland — 8 April 1899, Paris) was a notable French inventor and entrepreneur recognized for his significant contributions to the field of harmoniums and other keyboard free-reed instruments. His career flourished in Paris from 1839 until his death, where he operated a successful atelier under the name M. Kasriel. The workshop became particularly famous for its portable and compact harmoniums, including the Flûte-harmoniums—Kasriel's own variant of the "harmoniflutes," a hybrid of accordion and harmonium that gained popularity in France during the early 1860s—and the smaller "guide-chants," which were designed for choral accompaniment. Following his death, his grandsons, Louis Kasriel (10 October 1872, Paris — 22 December 1943, Auschwitz) and Albert Freitag-Marks (1869—1???), continued the family legacy by reopening the business in 1900 as Les Petits-Fils de M. Kasriel, expanding their offerings to include "standard" full-size harmoniums and free-reed organs. The company operated under external management from 1947 until 1984.

Born into a Jewish family in Krotoszyn, a town with roots dating back to the 15th century, Maurice immigrated to France in his youth, adapting his surname to a more French-sounding version, presumably Kassril. In 1839, he established a workshop in Paris that focused on manufacturing accordions and compact, foldable free-reed instruments, such as "Bible regals." Shortly after settling in Paris, Kasriel married Sara Kahn (ca. 1810—1891) in April 1839, with whom he had three children: his first son Édouard Kasriel (1839—1882) and two daughters, Adélaïde (1844—1883) and Cécile Kasriel (1856—1878). By the early 1850s, as his business gained a strong foothold across Europe, Kasriel began to expand internationally. In 1851, Ramchunder & Bros. was established in Bombay as the exclusive sales agent for the firm in India. Shortly thereafter, his teenage son, Édouard, went to oversee the launch of a North American division.

Édouard settled in St. Louis, Missouri, where he managed the U.S. headquarters of the business. In September 1858, he married Ernestine Dienemann (1828—1902), and between 1859 and 1863, they had three children in the United States. Around 1865, Edouard returned to France, where his father Maurice had expanded the family enterprise to new heights, earning a silver medal at the 1863 Toulouse industrial exhibition. However, Edouard ultimately lost interest in the business, choosing to leave it to pursue a career in painting. Maurice Kasriel continued to oversee the business until his later years, during which time his portable harmoniums and harmoniflutes won a gold medal at the Exposition Universelle in Paris in 1878. Maurice Kasriel passed away in April 1899 at the age of 84.

In 1900, the business was inherited by two of Maurice's grandchildren: Edouard's youngest son, Louis Kasriel, and his cousin Albert Freitag-Marks, the eldest son of Adélaïde, who had married Brazilian expatriate Simon S. Freitag-Marks (ca. 1820—ca. 1879) in Paris in September 1865. The two adopted the honorary brand Grandsons of M. Kasriel, unveiling an expanded product line at the Exposition Universelle, which now included standard full-size harmoniums, for which they received a silver medal. The company thrived over the following three decades, successfully reopening after World War I and reaching its peak in the early 1930s. In 1936, Louis Kasriel acquired the business of Albert Louis Chaperon (1881—1958), along with a substantial portfolio of historical piano and organ brands, including Debain et Cie, Rodolphe et Fils, H. Christophe & Étienne, and Cottino & Tailleur. That same year, Louis patented a significant improvement for transposing/non-transposing harmoniums, with a similar application for accordions introduced in 1938.

The onset of the Second World War brought a near-complete halt to instrument manufacturing in Europe. The Kasriel family suffered devastating losses during this period, as Louis Kasriel and his eldest son, violinist Raymond Edouard Kasriel (28 May 1900, Paris — 20 February 1945, Buchenwald), were arrested and murdered in Nazi concentration camps. The fate of Albert Freitag-Marks remains unknown; his mother, Adélaïde Kasriel, died in Rio de Janeiro in March 1883, and it is plausible that Albert and his siblings emigrated to Brazil to escape the war. In 1947, one of the surviving heirs, referred to as "Madame Kasriel" in existing records, transferred the business to Paul Eugène Fernand Pisson-Brunet (26 January 1891, Saint-Ouen — 30 June 1974, Rayol-Canadel-sur-Mer), a French piano manufacturer and owner of the Elcké brand. Pisson-Brunet continued to produce "Kasriel" instruments for several years. In 1955, he commissioned Jacques Fortin (1908—1994) to develop an electric harmonium for the company, which was successfully marketed as the "F-55" model. The firm relocated to the former facilities of Elcké in 1977, though production gradually declined. By 1984, with the cessation of operations, it marked the end of Kasriel as the last active harmonium manufacturer in France.