Officine Meccaniche or OM was an Italian car and truck manufacturing company, founded in 1918 in Milan as Societa Anonima Officine Meccaniche. It disappeared as such in 1975 subsumed into Iveco, but still exist as a forklift builder.
Read more about Officine Meccaniche: Origins, The OM Cars Era, Fiat Take-over and Post-war Years, The End of OM