2-methyl-4-(4-methyl-1-piperazinyl)-10H-thieno[2,3-b][1,5]benzodiazepine more commonly known as Olanzapine (oh-LAN-za-peen, sold as Zyprexa, Zyprexa Zydis, or in combination with fluoxetine, as Symbyax) was the third atypical antipsychotic to gain approval by the Food and Drug Administration (FDA), gaining approval in 1996 , and has become one of the most commonly used atypical antipsychotics. Olanzapine has been approved by the FDA for the treatment of schizophrenia, acute manic episodes in bipolar disorder, acute agitation associated with schizophrenia and bipolar disorder, maintenance treatment in bipolar disorder, and, with fluoxetine as the Symbyax formulation, for the treatment of depressive episodes associated with bipolar disorder. Off-label uses are listed below.

Olanzapine is manufactured and marketed by the pharmaceutical company Eli Lilly and Company, whose patent for olanzapine proper ends in 2011.