Jaffé, Sir Otto (1846–1929), businessman and philanthropist, was born 13 August 1846 in Hamburg, Germany, third son among four sons and five daughters of Daniel Joseph Jaffé (1809–74) and his wife Frederiké. Daniel Joseph Jaffé was a merchant in the Hamburg firm of Jaffé Brothers, who imported Irish linen, and in 1858 the family established their business in Belfast to deal directly with producers. Daniel Jaffé sold very large amounts of linen to Russia and to South and North America, and is credited with helping to develop the commercial networks within which the commodity was so successfully traded in the nineteenth century. He also established Belfast's first synagogue and Jewish school, in Great Victoria St. (1871). Otto Jaffé was 12 when he arrived in Belfast; he attended Mr Tate's school in Holywood, Co. Down, and finished his education in Switzerland. From 1865 to 1877 he was in charge of the family's business in the USA; he crossed the Atlantic forty times. Probably as a result of his experience of ocean travel, he initiated a campaign to report and destroy derelict ships in the seaways, which posed such a threat to shipping, particularly in the days before radar. In 1877, when his elder brothers retired from business, Otto Jaffé took over as head of the Belfast concern, and made a unique contribution to Belfast commercial and public life. In 1910 he opened the Jaffé mill on the Newtownards Rd, which employed hundreds of workers.
He was elected to Belfast corporation in November 1891, and took his seat for St Anne's ward in 1892. He represented St George's ward 1895–7, and Windsor 1897–1916 (as an alderman from 1904). In 1899 he was elected first lord mayor of the newly established county borough of Belfast, despite the opposition of two anti-semitic councillors. In March 1900, as he left office, he was knighted by the lord lieutenant in Dublin in recognition of his civic services, and also for his work with his wife, Paula Jaffé, in raising a fund of £10,000 for families of Boer war soldiers. He was again mayor in 1904, and was sheriff of the county. He served on Belfast harbour board and Belfast chamber of commerce, was a JP, and was a major contributor to the city's hospitals. He and other members of the family were life governors of the Royal Victoria Hospital, and in addition he gave £1,000 to the building fund.
Sir Otto was particularly involved in the provision of education. As chairman of the corporation's committee of technical education, he helped establish the new municipal technical institute in College Square, Belfast, and he was a member of the national board of technical education in Dublin. He was vice-chairman of the Belfast Society for the Extension of University Teaching, and contributed large sums to the Better Equipment Fund of QCB; around 1901 he gave 30 milligrammes of radium to the college. In 1905, his gift of a further amount of £3,000 made it possible for the college to match-fund a promised donation of £20,000 from Sir Donald Currie, a Scots businessman. New laboratories were opened in 1907, and the physiology laboratory was named after Jaffé. Among other activities, he was prominent in the first senate of QUB; his elder son, Arthur Daniel Jaffé (b. 1880), a barrister, was secretary to the commissioners established under the Irish universities act of 1908, which set up QUB.
Primary education, especially for the Jewish community, also interested him; in 1907 he built and equipped the Jaffé National Public Elementary School on the Cliftonville Rd, for Jewish children. Sir Otto was the main contributor to funds for a new synagogue in Annesley St., north Belfast, for the then-expanding Jewish population of that area; he opened it in August 1904, as lord mayor. He was life-president of the Jewish congregation in Belfast. Members of the Jaffé family were prominent in Jewish life and in the wider community in succeeding generations; Sir Otto's brothers included John Joseph Jaffé, who was president of Belfast chamber of commerce in 1883 and gave £1,000 to QCB. A sister, Jane Jaffé (1858–1907), married Israel Davis, one of the proprietors of the influential London-published Jewish Chronicle, and helped edit the journal from 1878 to 1906. She was an advocate of women's emancipation, and also a keen botanist. She had at least one daughter.
Sir Otto Jaffé was German consul in the north of Ireland from 1882; although he took British citizenship, and had given so generously to his adopted city and country, he was still linked in the public mind with Germany, because of his name and birth, and because some people believed all Jews were German. In the violently anti-German and latently anti-semitic atmosphere that developed in Belfast during the first world war, Sir Otto's household felt that they were under threat. He resigned from Belfast corporation in 1916, after twenty-five years of service, and moved to London, where he died on 29 April 1929. He was cremated at Golders Green on 2 May 1929, survived by his wife and two sons. He married (8 March 1879) Paula, daughter of Moritz Hertz of Brunswick, Germany.