| Actor | Actor | Number of letters | From | to | |
|---|---|---|---|---|---|
| Barth, Karl | Gut, Walter | 64 | 1929 | 1968 | |
| Kirschbaum, Charlotte von | Putsch, Hugo | 64 | 1931 | 1962 | |
| Barth, Karl | Verlag: Hodder & Stoughton Ltd. | 64 | 1933 | 1961 | |
| Barth, Karl | Freudenberg, Adolf | 64 | 1937 | 1968 | |
| Apolant, Sophie | Kirschbaum, Charlotte von | 64 | 0 | 1965 | |
| Barth, Karl | Schlunck, Rudolf | 63 | 1920 | 1930 | |
| Barth, Karl | Niemöller, Martin | 63 | 0 | 1967 | |
| Barth, Karl | Epprecht, Robert | 62 | 1913 | 1966 | |
| Barth, Karl | Studentenverbindung: Zofingia | 62 | 1930 | 1961 | |
| Emmerich, Gertrud | Kirschbaum, Charlotte von | 62 | 1932 | 1954 | |
| Barth, Karl | Immer, Karl | 61 | 1925 | 1967 | |
| Kirschbaum, Charlotte von | Pestalozzi, Rudolf | 61 | 0 | 1961 | |
| Kirschbaum, Charlotte von | Wagner-Simon, Thea | 61 | 0 | 1965 | |
| Barth, Karl | Geiger, Max | 61 | 1944 | 1968 | |
| Barth, Karl | Blaser, Emil | 60 | 1935 | 1968 | |
| Barth, Karl | Lüthi, Walter | 60 | 1936 | 1967 | |
| Barth, Karl | Wolf, Erik | 60 | 1945 | 1968 | |
| Barth, Karl | Herpel, Otto | 59 | 1919 | 1924 | |
| Barth, Karl | Peterson, Erik | 59 | 1921 | 1951 | |
| Barth, Karl | Verlag: Delachaux et Niestlé | 59 | 1943 | 1967 | |
| Barth, Karl | Kupisch, Karl | 59 | 1955 | 1968 | |
| Barth, Karl | Bieder, Werner | 58 | 1932 | 1968 | |
| Barth, Karl | Cordes, Martin Friedrich | 58 | 0 | 1967 | |
| Dehn, Günther | Kirschbaum, Charlotte von | 58 | 1938 | 1965 | |
| Hilfswerk der Evangelischen Kirchen Schweiz (HEKS) | Kirschbaum, Charlotte von | 58 | 0 | 1962 | |
| Barth, Karl | Kutter, Hermann | 57 | 1914 | 1965 | |
| Kirschbaum, Charlotte von | Lentrodt, Hans | 57 | 1930 | 1946 | |
| Handrich, Karl | Kirschbaum, Charlotte von | 57 | 0 | 1963 | |
| Kirschbaum, Charlotte von | Lombard, Johannes A. | 57 | 0 | 1965 | |
| Barth, Karl | Koechlin, Alphons | 56 | 1931 | 1961 | |
| Kirschbaum, Charlotte von | Kredel, Pauline | 56 | 0 | 1961 | |
| Barth, Karl | Hoch, Dorothee | 56 | 1931 | 1968 | |
| Barth, Karl | Reformierter Bund für Deutschland | 55 | 1922 | 1965 | |
| Barth, Karl | Ott, Heinrich | 55 | 1946 | 1967 | |
| Kirschbaum, Charlotte von | Lanzenstiel, Georg | 54 | 1935 | 1965 | |
| Kirschbaum, Charlotte von | Schwenzel, Günter | 54 | 0 | 1965 | |
| Barth, Karl | Boué, Edgar | 53 | 0 | 1968 | |
| Barth, Karl | Weidmann, Hans | 53 | 1934 | 1968 | |
| Barth, Karl | Maurer, Adolf | 53 | 1935 | 1966 | |
| Karwehl, Hans Martin | Kirschbaum, Charlotte von | 53 | 0 | 1958 | |
| Barth, Karl | Wilhelm, Oscar | 52 | 1921 | 1965 | |
| Barth, Karl | Schlink, Edmund | 52 | 1928 | 1968 | |
| Barth, Karl | Koch, Werner | 52 | 1931 | 1967 | |
| Barth, Karl | Lachat, William | 52 | 0 | 1966 | |
| Barth, Karl | Iwand, Hans Joachim | 52 | 1934 | 1960 | |
| Barth, Karl | Buess, Eduard | 52 | 1945 | 1968 | |
| Barth, Karl | Weber, Otto | 51 | 1930 | 1964 | |
| Barth, Karl | Eichholz, Georg | 51 | 1932 | 1968 | |
| Barth, Karl | Thurneysen, Marguerite | 50 | 1916 | 1967 | |
| Barth, Karl | Hess, Hans Erich | 50 | 1925 | 1966 |