Harold Smith, played by Lenny Von Dohlen, has agoraphobia and thus does not leave his home. Laura Palmer met him when she delivered him his meals. Laura gave Harold her secret diary for safe-keeping, because BOB can't see him. Harold grows and develops new orchid species in his home.
Donna Hayward, Laura's best friend, befriended him during her investigation into her death. Their relationship ended badly when Donna attempted to steal Laura's secret diary. Harold was later found dead with scraps of the diary around him, the cause of death being ruled as suicide. His suicide note read "J'ai une âme solitaire." (Roughly translated from the French: "I've got a lonely soul" or "I am a lonely soul.") This note is oddly similar to the one left by late Boston lead vocalist Brad Delp.