Claus Spreckels (July 9, 1828 – December 26, 1908) was a German-born American industrialist in California and Hawaii, during the kingdom and republican periods of the islands' history. He founded or was involved in several enterprises, most notably the company that bears his name, Spreckels Sugar Company.

Early life and family Spreckels was born in Lamstedt, in the Kingdom of Hanover, a constituent kingdom of the German Confederation. Spreckels was the eldest of six children of the farmer John Diederich Spreckels (1802–1873) and his wife Gesche Baak (1804–1875), a family that had occupied a homestead in Lamstedt for many generations. He grew up in Lamstedt and attended elementary school. After the bad harvests of 1845 and 1846, the resulting inflation and hunger crisis reached its peak in 1847. Spreckels emigrated to the United States in 1848 at the age of 19 to start a new life, with only one German thaler in his pocket, which upon arrival in the US, he exchanged for 75 cents. (Equivalent to about $30 in 2023 dollars.) (The Consumer Price Index estimated inflation from 1848 to 2023, rounded to two significant figures.) Spreckels settled in Charleston, South Carolina, working as a grocery clerk, taking over the grocery store after a year and a half by buying it on credit from the retiring shop owner.

In 1852, he married his childhood sweetheart, Anna Christina Mangels (September 4, 1830 in , Kingdom of Hanover, German Confederation – February 15, 1910, San Francisco, California), who had immigrated to New York City with her brother three years earlier. They had 13 children, five of whom lived to maturity. His surviving sons were John D. Spreckels (1853-1926), Adolph B. Spreckels (1857-1924), Claus August (1858-1946), and Rudolph Spreckels (1872-1958). He had one daughter, Emma Claudina (1870-1924), who married Watson Ferris Hutton. The remaining children died in childhood, in several cases, within a few months of each other, either from diphtheria or from other unspecified pandemic diseases, possibly cholera.

In California Early business ventures

In 1854, Claus and his family left Charleston for New York City, where he operated a grocery with his brother-in-law, Claus Mangels. In 1855, he was visited by his younger brother Bernhard, who operated a grocery store in San Francisco and was en route back to their home town of Lamstedt to marry. Bernhard regaled Claus with stories about the city and its booming post-Gold Rush economy. Already disliking New York City and sensing an opportunity, Spreckels soon sold his share of the grocery business there to his brother-in-law and bought out Bernhard's San Francisco grocery, relocating there with his family in 1856.

After about a year of operating a successful grocery in San Francisco, he again grew restless with the lack of growth opportunity in that line of business. Noting the generally poor quality of San Francisco "quick-brewed beer" of that time, he saw brewing as an industry with strong growth potential. He partnered again with Claus Mangels and with a younger brother, Peter Spreckels, to start a brewery and sold off his grocery business soon after. Spreckels and his partners opened the Albany Brewery on Everett St near Fourth Street (now Yerba Buena Gardens) in 1857, and soon afterward opened a saloon, the Albany Malt House, across the street. The brewery's first product was a cream ale, but later added a German-style lager and a steam beer, which, by some accounts, introduced steam beer to California.

Brewing proved a sometimes difficult line of work. Beermaking required constant monitoring for temperature, something that might be ignored when a shift change happened, requiring Spreckels to come in late at night and monitor the process himself. He later stated that he often slept no more than four hours per day for months on end. The brewery and saloon were successful and became the second largest brewery in San Francisco, but never managed to surpass competitor John Wieland's Philadelphia Brewery for the top position. Spreckels himself never made more than a modest income after splitting the earnings with his partners.

Building a sugar business: 1863–1865 Spreckels saloon was located in the same area as George Gordon's San Francisco and Pacific Sugar Refinery and frequented by some of its workmen. Spreckels had overheard a conversation between these workmen discussing the wastefulness of the sugar refining process at their factory, which allowed large amounts of sugar liquor to overflow and run into the sewers. Spreckels sensed that if the refinery could still turn a profit while wasting so much of its product, then the profit potential in sugar must be enormous. An additional factor was the outbreak of the American Civil War in 1861, which cut off the North from Southern sugar supplies, causing demand to outstrip supply.

In 1863, Spreckels decided to go into the sugar refining business, leaving management of the brewery in the hands of his partners. In order to familiarize himself with the process of sugar refining, he relocated to New York City (then the center of the American sugar industry) for several months, taking an entry-level night shift job at the Charles W. Durant sugar refinery and learning all aspects of the process. During the day, he toured other sugar refineries, asking detailed questions about their process. Spreckels had his eldest son John accompany him on this extended trip and included him on factory tours so that he would learn the business as well. While in New York City, Spreckels took advantage of the opportunity to purchase a full set of sugar refining equipment from the recently bankrupted United States Refinery, having it shipped around Cape Horn to San Francisco.

In 1864, Spreckels opened the Bay Sugar Refining Company, the first of a series of sugar refining enterprises, establishing a factory at Union and Battery Streets, near the San Francisco waterfront. Claus Spreckels would again partner with Claus Mangels and Peter Spreckels, but also brought in financers Hermann Meese and Louis Meyer as partners. At the same time, he finally sold off his remaining shares of the Albany Brewery, leaving that business in the hands of Mangels and Peter Spreckels. In a letter to a colleague, George Gordon wrote, "I am greatly annoyed at the action of that fool, Spreckles in building another sugar refinery for which there is no room." However, the new company expanded rapidly, and using price war tactics, grew its market share of sugar in California at the expense of Gordon's San Francisco and Pacific company.

In 1865, Spreckels told his partners that he wanted a substantial amount of the company's profits reinvested in doubling the size of the refinery. The partners balked at this plan, preferring their existing comfortable dividends over the immediate loss of income and risk involved in expansion. Claus then quit the company, selling controlling shares to Meese and Meyer, later stating that he preferred to "start afresh rather than being hampered by the conservatism of frightened little men".

Building a sugar empire: 1865–1881

Soon after selling his refinery, Spreckels and his family left for an extended stay in Germany. He set about learning the details of the specialized processes of sugar beet agriculture and refining, which were relatively little-known in the United States, even taking a workman's position in a beet sugar refinery in Magdeburg for several months. He returned to California in early 1867, with a supply of sugar beet seeds that he had brought back from Germany. He publicized sugar beet growing to farmers around the Central Valley, promising great profits, but was unable to find growers due to the highly labor-intensive nature of the sugar beet-growing process. He instead set about returning to the cane sugar refining business.

Spreckels opened the California Sugar Refinery, located at Eighth and Brannan Streets in San Francisco, in April 1867. He again partnered with Peter Spreckels and Claus Mangels and brought in new partners Frederick Hagemann and Henry Horstman. However, unlike his previous enterprises, he maintained full controlling interest in the new company. The new refinery benefited from new technologies, including exclusive patents by Spreckels. He introduced granulated sugar and sugar cubes, which had been recently developed in Europe, to the American market. Before these products were introduced, sugar was sold in the form of hard sugarloaves that the consumer had to break up using special tools or pay extra for a grocer to do it. Spreckels's technological innovations also vastly increased his product output, producing as much sugar in one day as his previous refinery had produced in three weeks. With these new products and production capacity, his new company would begin to outpace his competitors, the Bay Sugar Refinery, now in the hands of his former partners, and George Gordon's San Francisco and Pacific Sugar Refinery.

This business achievement came at a marked personal cost, however. In 1869, overwork and stress had led to severe burnout and a mental breakdown, characterized by memory loss and other physical and mental symptoms. His doctors advised him to withdraw from all business activity. Spreckels left management of the California Sugar Refinery in the hands of his partners and spent the next 18 months over 1869 and 1870 traveling with his family in Europe. This trip included a course of hydrotherapy at the spa town of Karlsbad, Bohemia. He returned to San Francisco in early 1871 with his health and vigor fully restored.

Spreckels faced additional competition from 1870 to 1873 when E. H. Dyer operated the California Beet Sugar Company, the first successful sugar beet refinery in the United States, across the San Francisco Bay in Alvarado, California. Nevertheless, by 1874, Spreckels's company was claiming to be the largest sugar refinery in California and by 1880, he had a near-monopoly on sugar production in California. Claus Spreckels was hailed in the Hawaiian and California press as the "Sugar King".

With a steady supply of raw sugar coming from his Hawaiian operations, Spreckels announced that he would be relocating and expanding his refinery. The company purchased six blocks of land in the Potrero Point area in an industrial part of San Francisco several miles south of downtown. The location was strategically located near to where wharf facilities could be built along San Francisco Bay and also near to the Southern Pacific Railroad lines. The enormous twelve-story factory building was completed and began operations in 1881. Spreckels also developed housing and hotel space for over 200 workers, and the new neighborhood at Potreo Point would become the core of the area later known as Dogpatch.

Building Santa Cruz County

Facing competition from the California Beet Sugar Company in the early 1870s, Spreckels began shopping for land outside of San Francisco where he could further experiment with sugar beet cultivation. In 1872, Rafael de Jesus Castro and his wife Maria Soledad Cota de Castro, the owners of a large portion the former Mexican land grant Rancho Aptos, were undergoing a divorce and needed to liquidate their community property. Learning that the land was for sale, Spreckels quickly made an offer to buy out their property in cash, and soon after bought additional tracts from the Castro's sons, who had been deeded other portions of Rancho Aptos. In all, Spreckels purchased over 550 acres for his estate. In addition to planting sugar beets on a portion of the acreage, he also decided to build a second home on the ranch, allowing the Spreckels family a retreat away from San Francisco. He would go on to build an extensive ranch complex and, later, a large resort hotel.