Sir Gerard Augustus Lowther, 1st Baronet GCMG CB PC (16 February 1858 – 5 April 1916) was a British diplomat.
Lowther was educated at Harrow and entered the diplomatic service in 1879. He served in Tokyo, Budapest, and Washington, before he in August 1901 was appointed Envoy Extraordinary and Minister Plenipotentiary in Santiago, Chile. He arrived at Santiago to take up his position in March 1902.
Lowther later served in Tangier and finally as Ambassador in Constantinople. He is known for distributing anti-Semitic texts during his time in Constantinople, playing a crucial role in the spread of Arab Anti-Semitism.
He was made a Companion of the Order of the Bath in 1904, a Knight Commander of the Order of St Michael and St George and a Privy Counsellor in 1908 and a baronet in 1914 and promoted to Knight Grand Cross of the Order of St Michael and St George in 1911.
Lowther was the second son of William Lowther and his wife Charlotte Alice, daughter of James Parke, 1st Baron Wensleydale. James Lowther, 1st Viscount Ullswater, was his elder brother and Sir Cecil Lowther his younger brother.