| Monck, Nugent | Nugent Monck | Director | 1925 - 1928 | 3 | 1 |
| Miller, Jonathan | Jonathan Miller | Director | 1974 | 1 | 1 |
| Metscheva, Liljana | Liljana Metscheva | Director | 1974 | 1 | |
| Mackey, Karl | Karl Mackey | Director | 1973 | 1 | |
| Mervild, Kaj | Kaj Mervild | Director | 1928 | 1 | 1 |
| Marshall, T. H. | T. H. Marshall | Director | 1928 | 1 | 1 |
| Moulios, Giorgos | Giorgos Moulios | Director | 1977 | 1 | |
| Michaelsen, Ingrid Elise | Ingrid Elise Michaelsen | Director | 1978 | 1 | |
| Min, Zhan | Zhan Min | Director | 2006 - 2010 | 7 | |
| Mardžanov, Konstantin | Konstantin Mardžanov | Director | 1912 | 1 | |
| Menegatti, Beppe | Beppe Menegatti | Director | 1974 - 2007 | 7 | |
| Millerd, Bill | Bill Millerd | Director | 1978 | 1 | |
| Meißner, Johannes | Johannes Meißner | Director | 1897 | 1 | |
| Meacham, Michael | Michael Meacham | Director | 1975 - 1979 | 2 | |
| Michailidis, Kostis | Kostis Michailidis | Director | 1946 - 1980 | 9 | |
| McNern, Samantha | Samantha McNern | Director | 2013 | 1 | |
| Morahan, Christopher | Christopher Morahan | Director | 1958 - 1979 | 3 | 1 |
| Meinholtz, Rolland | Rolland Meinholtz | Director | 1972 | 1 | 1 |
| Moreno, Angel García | Angel García Moreno | Director | 1981 | 1 | |
| Morera, José María | José María Morera | Director | 1983 | 1 | |
| Mrsán, János | János Mrsán | Director | 1983 | 1 | |
| Moskowicz, Imo | Imo Moskowicz | Director | 1965 | 1 | |
| Marlette, Don | Don Marlette | Director | 1978 | 1 | |
| McFarland, Charles | Charles McFarland | Director | 1987 | 1 | |
| Mokrowiecki, Marek | Marek Mokrowiecki | Director | 1983 | 1 | |
| Morand, Philippe | Philippe Morand | Director | 1993 | 13 | |
| Metodiev, Stefan | Stefan Metodiev | Director | 1994 | 1 | |
| Mancinelli-Cahill, Maggie | Maggie Mancinelli-Cahill | Director | 2000 | 1 | |
| McCasland, Steven, Carl | Steven Carl McCasland | Director | 2012 | 1 | |
| Markle, Christopher | Christopher Markle | Director | 1984 | 1 | |
| Mitchinson, Liam | Liam Mitchinson | Director | 2012 | 1 | |
| Murray, Nancy | Nancy Murray | Director | 2013 | 1 | |
| Miller, George | George Miller | Director | 2013 | 1 | |
| Ming, Ren | Ren Ming | Director | 2014 - 2021 | 13 | |
| Manzaneque, Manuel | Manuel Manzaneque | Director | 1975 - 1985 | 2 | |
| Myska, Edward | Edward Myska | Director | 1986 | 1 | |
| Mark, James | James Mark | Director | 1967 - 2006 | 5 | |
| Moshinsky, Elijah | Elijah Moshinsky | Director | 1987 | 1 | 1 |
| Mann, Catherine | Catherine Mann | Director | 2007 | 1 | |
| Meuleman, Marcelle | Marcelle Meuleman | Director | 1990 | 1 | |
| Manfrè, Walter | Walter Manfrè | Director | 1991 | 1 | |
| Müther, Adelheid | Adelheid Müther | Director | 1990 - 2003 | 42 | |
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