Mykola Leontovych
Mykola Leontovych specialised in a cappella choral music. He is remembered today mostly through the musical works he left behind, which include over 150 choral compositions. These range from artistic arrangements of folk songs, religious works (including his liturgy), cantatas, and choral compositions set to the words of various Ukrainian poets. His two most famous works are the choral miniatures "Schedryk" and "Dudaryk".
Tibor Serly
He greatly admired and became a young apprentice of Béla Bartók. 
For the most part his efforts were highly praised, both by Bartók and by colleagues. Bartók's Viola Concerto took two or three years of Serly's efforts to compile from sketches into a performable piece. It is now one of the most widely performed viola pieces. One of Serly's most famous original works is Rhapsody for Viola and Orchestra. His work bringing Bartók's work to fruition has paid off in the sense that his works are often paired with those of his better known teacher, on recordings and in live performance.