George Ion Diamandy or Diamandi, first name also Gheorghe or Georges, was a Romanian politician, dramatist, social scientist, and archeologist. Although a rich landowner of aristocratic background, he was one of the pioneers of revolutionary socialism in France and Romania, obtaining international fame as founder of L'Ère Nouvelle magazine. He was an early affiliate of the Romanian Social-Democratic Workers' Party, but grew disenchanted with its radical policies, and, as a member of its "generous youth" faction, played a major part in dissolving it. With other members of this reformist group, he joined the National Liberal Party, serving as one of its representatives in Chamber.

Carla Henius was a German operatic soprano and mezzo-soprano, voice teacher and librettist. She played a decisive role in promoting recent works by composers such as Arnold Schönberg, Karlheinz Stockhausen and Luigi Nono for the stage. She wrote the libretto for an opera by Aribert Reimann.
(Bartolomeo) Ortensio Mauro was an Italian writer and librettist.
Prince Maciej Radziwiłł was a Polish-Lithuanian noble (szlachcic), composer and librettist.

Euan Francis Barclay Tait is a Welsh-Scottish Librettist, poet, retreat leader, and teacher. He works internationally with choral composers. Tait has worked with Paul Spicer, Kim Andre Arnesen, Timothy Tharaldson, Dominic McGonigal, Carson Cooman, Chris Hutchings, and Janet Oates amongst numerous others.

Olav Anton Thommessen is a Norwegian contemporary composer. His main compositions include Et glassperlespill and Gjennom Prisme. Thommessen has played a significant role in aesthetic discourse in Norway and is known for his strong defence of modernist and atonal music and criticism of younger composers' revival of non-modernist and tonal music; a debate between Thommessen and Marcus Paus in 2015 was described as "the biggest public debate about art music" in Norway since the 1970s and Thommessen was revealed to be the eponymous teacher and librettist behind Paus' opera The Teacher Who Was Not To Be.
Leelo Tungal is an Estonian poet, children's writer, translator, editor and librettist.

Josef Wenzig was a Bohemian writer and author of librettos.