Sir Benjamin Lee Guinness, 1st Baronet (1 November 1798 – 19 May 1868) was an Irish brewer and philanthropist.
Born in Dublin, he was the third son of the second Arthur Guinness (1768–1855), and his wife Anne Lee, and a grandson of the first Arthur (1725–1803), who had bought the St. James's Gate Brewery in 1759. He joined his father in the business in his late teens, without attending university, and from 1839 he took sole control within the family. From 1855, when his father died, Guinness had become the richest man in Ireland, having built up a huge export trade and by continually enlarging his brewery.
In numbers, sales of his single and double stouts had been 78,000 hogsheads in 1855, which he nearly trebled to 206,000 hogsheads in 1865. Of these, some 112,000 were sold in Ireland, as the rural economy recovered from the 1840s potato famine, and 94,000 were exported to Britain.
By 1870, soon after his death, sales had risen further to 256,000 hogsheads, of which 120,000 were exported to Britain. Benjamin had also created the capacity for his sons to expand sales much further, and by 1879 these reached 565,000 hogsheads.
As a part of the brewery expansion, and to ensure deliveries, he invested in the new Irish railway companies from the 1840s. By 1867 the firm owned £86,000-worth of Irish railway stock (worth over £135m in 2013 values, taken as a share of GDP).
In 1851 he was elected the first Lord Mayor of Dublin under the reformed corporation.
In 1863 he was made an honorary LL.D. (Doctor of Laws) by Trinity College Dublin, and on 15 April 1867 was created a baronet by patent, in addition to which, on 18 May 1867, by royal licence, he had a grant of supporters to his family arms.
Guinness was elected to the House of Commons in 1865 as a Conservative representative for Dublin City, serving until his death. His party's leader was Lord Derby. Previously he had supported the Liberal Lord Palmerston, but in the 1860s the Liberals proposed higher taxation on drinks such as beer. Before 1865 the Irish Conservative Party did not entirely support British conservative policy, but did so after the Irish Church Act 1869. The government's most notable reform was the Reform Act 1867 that expanded the franchise.