Otto the Grouch

 Otto the GROUCH  is  OSCAR THE GROUCH  ' s baby brother. He ' s also the baby brother of Ernest the  GROUCH  &  OSCAR  ' s sister  Bunny , making him the 3 rd son o f  MR .  &  MRS . GROUCH . Otto is both seen & mentioned in the 1976 book   How to Be a  GROUCH .

Books

 *  How to Be a  GROUCH  ( 1976 )