Colonel Sir Rowland Blennerhassett, 1st Baronet (1741 - 14 March 1821) was an Anglo-Irish lawyer and baronet.

Blennerhassett was the son of Robert Blennerhassett and Frances Yielding. He was the great-grandson of Robert Blennerhassett MP.^[1]

He trained as an attorney and practised law.^[2] He was the colonel of the 'Laune Rangers' militia regiment of volunteers from 1779 to 1782. Between 1796 and 1797 he was a Justice of the Peace in County Kerry. Blennerhassett resettled his family at Cahirmoreaun, just outside Tralee, renaming both the house and the village Blennerville in his family's honour. He built a large new family home at Churchtown House, Knockane. In 1800 he was granted permission to hold four fairs a year and one market a week in Blennerville, which providing him with extra income. Blennerhassett established in Blennerville a windmill around 1800 which still exists and a Church of Ireland school, called the Erasmus Smith School, in 1812. On 22 September 1809 he was created a baronet of Blennerville in the County of Kerry, in the Baronetage of the United Kingdom.^[3] He was confirmed the right to bear the family coat of arms a year earlier.

Blennerhassett married his first cousin, Millicent Agnes Yielding, the daughter of Richard Yielding, on 31 October 1762; she was killed in an accident in 1801, receiving a blow from one of the sails of their windmill. Together, they had five children:^[1]

• Sir Robert Blennerhassett, 2nd Baronet (26 January 1769 – 21 September 1831), married Rosanna Blennerhassett
• Richard Francis Blennerhassett (23 May 1772 - November 1827), married Agnes Denny, daughter of Sir Barry Denny, 1st Baronet
• Arthur Blennerhassett (27 October 1776 – 31 May 1839), married Hon. Helena Jane Mullins, daughter of Thomas Mullins, 1st Baron Ventry
• Rowland Blennerhassett (26 December 1780 – 12 April 1854), married Letitia Hurly
• William Blennerhassett (26 December 1780 - 1842), married Elizabeth Blennerhassett