Here is the interesting list of mathematicians, who work in Operator theory and related topics. The list is under permanent reconstruction...

Baghwati Duggal

Christoph Schmoeger

Eve Oja

Gospava Djordjevic

Gradimir V. Milovanovic

Harald Wimmer

Jerry J. Koliha

Karl-Heinz Foerster

Laura Burlando

Lawrence A. Fialkow

Miroslav Ciric

Mostafa Mbekhta

Pietro Aiena

Robert E. Hartwig

Robin Harte

Stevan Pilipovic

Themistocles Rassias

Vladimir Rakocevic

Woo Young Lee

Yimin Wei 

Young Min Han