Gordon Douglas (monk),
Gordon Douglas has traditionally been seen as the first European to become ordained as a Bhikkhu in Southeast Asia although Laurence Carroll (U Dhammaloka) and others are now understood to have been earlier.1 He was ordained in Siam in 1899 or 1900 and assumed the name Bhikkhu Asoka or Ashoka.2
An online summary is Theravāda Spirituality in the West.
U Dhammaloka (Burmese: ဦးဓမ္မလောက; c. 1856 – c. 1914) was an Irish-born hobo (migrant worker)1 turned Buddhist monk, atheist critic of Christian missionaries, and temperance campaigner who took an active role in the Asian Buddhist revival around the turn of the twentieth century.
Dhammaloka was ordained in Burma prior to 1900, making him one of the earliest attested western Buddhist monks. He was a celebrity preacher, vigorous polemicist and prolific editor in Burma and Singapore between 1900 and his conviction for sedition and appeal in 1910–1911. Drawing on western atheist writings, he publicly challenged the role of Christian missionaries and by implication the British empire.
Found in the abstract of Rewriting the History of Early Western Buddhist Monastics.