Nicholas J. Clayton, architect, was born on November 1, 1840, in Cloyne, County Cork, Ireland, the son of Nicholas Joseph and Margaret (O'Mahoney) Clayton. In 1848, after the death of his father, he and his mother immigrated to Cincinnati, Ohio. Clayton's military records indicate that before the Civil War he worked as a plasterer in Cincinnati, New Orleans, Louisville, Memphis, and St. Louis. Between 1862 and 1865 he served as a yeoman in the United States Navy. After his discharge in 1865, he returned to Cincinnati, where he was listed in city directories as a marble carver (1866), carver (1870), and architectural draftsman (1871). He traveled to Houston from Cincinnati in October 1871. In 1872 he moved to Galveston to take a position as supervising architect for the construction of the First Presbyterian Church, designed by the Memphis, Tennessee, architects Jones and Baldwin. He remained in Galveston and began the practice of architecture there.
Clayton was responsible for so many of the major public, commercial, and residential buildings constructed in Galveston during the 1870s, 1880s, and 1890s that Howard Barnstone described this period in the city's history as the "Clayton Era." Clayton was a High Victorian architect. His buildings were exuberant in shape, color, texture, and detail. He excelled at decorative brick and iron work. His High Victorian predilections were evident not only in his buildings of the 1870s, but in those influenced by the Queen Anne movement of the 1880s, the Richardsonian Romanesque movement of the late 1880s and 1890s, and the revival of Renaissance classicism after 1890. What made Clayton's architecture so distinctive in late nineteenth-century Texas was the underlying compositional and proportional order with which he structured the display of picturesque shapes and rich ornament.
His first known independent work was St. Mary's Church (now St. Mary's Cathedral) in Austin (1873–84). He designed many parish churches and other institutional buildings in the Catholic dioceses of Galveston, Dallas, and Alexandria, Louisiana. He also produced major church and institutional buildings for Catholic religious orders, especially the Sisters of Charity of the Incarnate Word, the Ursuline Sisters, the Jesuits, and the Congregation of Holy Cross. His religious architecture accounted for the broadest geographical distribution of his work outside Galveston. Clayton's major ecclesiastical works included St. Patrick's Church, Galveston (1874–77, reconstruction 1901–02); Eaton Memorial Chapel, Galveston (1878–79); Sacred Heart Church, Palestine (1890–03); Grace Episcopal Church, Galveston (1894–95); St. Patrick's Church, Denison (1896–98); Sacred Heart Cathedral, Dallas (1896–1902); and the dome of the second Sacred Heart Church, Galveston (1910). He also was the architect of St. Mary's Infirmary, Galveston (1874–76, demolished); Ursuline Academy, Dallas (1882, 1887–90, 1901–02, 1906–07, demolished); additions to Incarnate Word Academy, Houston (1888–89 and 1899, demolished; 1905, extant); St. Edward's University, Austin (1888–96, 1903, 1907); Ursuline Academy, Galveston (1891–95, demolished); and St. Joseph's Infirmary, Houston (1892–94, 1895, demolished).
Among Clayton's foremost public buildings were the Galveston Electric Pavilion, the first building in Texas with electric lighting (1881, destroyed); Harmony Hall, Galveston (1881–83, demolished); the Masonic Temple, Galveston (1882–84, demolished); the Beach Hotel, Galveston (1881–83, destroyed); John Sealy Hospital, Galveston (1888–89, demolished); and the University of Texas Medical Department Building, Galveston (1888–91). Clayton served on an advisory board for the construction of the dome of the Capitol in Austin (1887) and was responsible for specifying furnishings for the building (1888).
His major commercial buildings included the International-Great Northern Railway General Offices Building, Palestine (1879, demolished); the Gulf, Colorado and Santa Fe Railway General Offices Building, Galveston (1881–82, 1892, destroyed); the Greenleve, Block, and Company Building, Galveston (1881–82, altered); the H. M. Trueheart and Company Building, Galveston (1881–82); the W. L. Moody Building, Galveston (1882–83, altered); the Galveston News Building (1883–84, defaced); the R. E. Stafford Bank and Opera House, Columbus (1886–87); the Clarke and Courts Building, Galveston (1890); the Adoue and Lobit Bank Building, Galveston (1890–91, defaced); the Hutchings-Sealy Building, Galveston (1895–96); the James Fadden Building, Galveston (1896–97); and the Star Drug Store Building, Galveston (1909).
Clayton was the architect of numerous houses, among which were the Van Alstyne House, Houston (ca. 1878, demolished); the Adoue House, Galveston (1881–82, demolished); the Blum House, Galveston (1884–85, demolished); the Trueheart House, Galveston (1884–86, demolished); and the Gresham House, Galveston, also known as the Bishop's Palace (1885–92). Major concentrations of Clayton's buildings are in the Strand Historic District and the East End Historic District in Galveston.
During the course of his career, Clayton was twice involved in partnerships: with the engineer Michael L. Lynch in the firm of Clayton and Lynch (1877–81), and with Patrick R. Rabitt, Jr. in the firm of N. J. Clayton and Company (1890–99). Clayton was a founding member of the Texas State Association of Architects and a member of the Western Association of Architects. As a result of the Western Association's merger with the American Institute of Architects in 1889, Clayton became a member and fellow of the AIA. He served a term as vice president of the Southern Chapter of the AIA (1895–96).
His professional practice declined precipitously after 1900. Protracted litigation that he instigated after the controversial awarding of a commission to design a new Galveston County Courthouse in 1897 and the decline of new construction activity in Galveston in the aftermath of the Galveston hurricane of 1900 were contributing factors. In March 1903 he declared bankruptcy. He never recovered financially. Although he continued in practice until his death, he never obtained subsequent major architectural commissions.
Clayton married Mary Lorena Ducie of Galveston on July 6, 1891. They had five children. Clayton was a parishioner of St. Patrick's Church. He was a member of the Galveston Garten-Verein and the Catholic Knights of America, the Knights of Columbus, and the Ancient Order of Hibernians. He died in Galveston on December 9, 1916, and is buried there at Calvary Cemetery. His architectural drawings and office records are deposited in the Galveston and Texas History Center of the Rosenberg Library and the Galveston County Historical Museum, both in Galveston, and the Barker Texas History Center and the Architectural Drawings Collection, both at the University of Texas at Austin.