Markus or Marcu Glaser (April 25, 1880 – May 25, 1950) was an Imperial Russian-born German cleric, Apostolic Administrator of the Roman Catholic Diocese of Iaşi.

Born in the village of Landau in what is now Ukraine to a Black Sea German family deported from southern Russia, he studied at the Saratov seminary before continuing his education at the Collegium Germanicum et Hungaricum in Rome.

[1] Requests by the nuncio for official recognition of Glaser's position were denied by the Religious Affairs Ministry in April and June 1945.

Starting in 1945, he was subjected to a series of lengthy and difficult interrogations before Soviet authorities lasting four years and dealing with his activity in Odessa and Iaşi, as well as a supposed visit to Germany in 1942.

Following the arrest of Durcovici in June 1949, he once again took over the running of the diocese, but the authorities of the new communist regime prevented him from carrying out his regular duties.