Saint Malo (also known as Maclou and, in Latin, as Maclovius or Machutus) was the mid-6th century founder of Saint-Malo in Brittany, France.

Details of Malo's career are preserved in three medieval 'Lives' which seem to include incidents associated with several different people of similar names. Despite this confusion, it appears that Malo was born about the year 520, probably in Wales.

Voyages with Saint Brendan
Malo is said to have been baptized by Saint Brendan and to have become his favourite disciple. However, serious doubt has been cast on the authenticity of this section of his life. He is said to have been one of those specially selected by that holy man for his oft-described voyage.

It was traditionally from Llancarfan Abbey that Saint Brendan and his disciple, Malo, with numerous companions set forth for the discovery of the "Island of the Blest". He then put to sea on a second voyage and visited the Island of Cézembre, in the seaward front of St Malo, where he tarried for some time. It was supposedly on the occasion of his second voyage that he evangelized the Orkney Islands and the northern isles of Scotland. It is remarkable that Saint Brendan also laboured at Cézembre where he is said to have had a hermit's cell on a precipitous rock in the sea, whither he often retired. This may be the derivation of the association between the two men, although Baring-Gould suggested that, in this case, Brendan is a mistake for Branwaladr.

Breton evangelist
At Aleth, opposite St Malo, Malo placed himself under a venerable hermit named Aaron, on whose death in 544, he succeeded to the spiritual rule of the district subsequently known as St Malo, and was consecrated first Bishop of Aleth.

In old age the disorder of the island compelled Saint Malo to leave, but the people soon begged the saint to come back. On his return matters were put right, and the saint, feeling that his end was at hand, determined to spend his last days in solitary penance. Accordingly he proceeded to Archambiac, a village in the Diocese of Saintes, where he passed the remainder of his life in prayer and mortification. His death is chronicled on 15 November, a Sunday, in the year 621 (although this may have been a different saint named Marcoult).