Main Characters Dr. Nikki Alexander 171 main appearances Prof. Leo Dalton 106 main appearances Jack Hodgson 95 main appearances Dr. Harry Cunningham 94 main appearances Prof. Samantha "Sam" Ryan 60 main appearances Clarissa Mullery 59 main appearances Dr. Thomas Chamberlain 49 main appearances Trevor Stewart 24 main appearances Cara Connelly 16 main appearances Professor Gabriel Folukoya 20 main appearances Velvy Schur 20 main appearances Simone Tyler 10 main appearances Dr. Adam Yuen 4 main appearances