 Hanna @-@ Barbera bought out the first cast 's contracts and hired new actors for the second season . This cast featured Quinton Flynn as Jonny , John de Lancie as Dr. Quest , Granville Van Dusen ( for the first two episodes ) and Robert Foxworth as Race , Jennifer Hale as Jessie , and Rob Paulsen as Hadji . Paulsen previously voiced Hadji in the two Quest telefilms . Don Messick attempted to reprise his classic role as Dr. Quest , but was forced into retirement by a stroke during early sessions . Van Dusen voiced Bannon in the 1986 Quest series , and Foxworth took over the part after auditioning for Dr. Quest . Frank Welker reprised his role as Surd in the second season . Several notable guest stars included Kevin Conroy , Earl Boen , Clancy Brown , Robert Ito , James Shigeta , Irene Bedard , Lucy Liu , Brock Peters , Tristan Rogers , Edward Asner , Julian Sands , Helene Udy , Mayim Bialik , Mark Hamill , Andreas Katsulas , Jeffrey Tambor , Dorian Harewood , Clive Revill , Kenneth Mars , Nick Chinlund , Clyde Kusatsu , Dean Jones , Thomas Gibson , Sarah Douglas and Carl Lumbly . Season two writer Lance Falk has also regretted not thinking about veteran voice actor John Stephenson , who was the very first voice of Dr. Quest , for a guest role . 
