'OM' was the designation of Allied convoys (together with a numerical and sometimes a literal suffix) plying the route from Oran, Algeria, to Marseille or Toulon, France, and as such reciprocals of the 'MO' series (October 1944/January 1945).

The first such convoy was OM.16 which departed Oran on 26 October 1944 with four merchant vessels (three US and one Norwegian), and the last of these 17 convoys was OM.31 of 8/12 January 1945 with 15 merchant vessels (13 US, one British and one Dutch).