Which of the following is not an antipsychotic used for bipolar disorder?

Haloperidol is the correct choice for this question as it is primarily classified as a typical antipsychotic, historically used for the treatment of schizophrenia and other psychotic disorders. While it can be used in certain acute situations related to bipolar disorder, it is not specially indicated for the treatment of bipolar disorder itself, especially in the same way as the other options listed.

In contrast, Saphris, Seroquel, and Latuda are atypical antipsychotics that have been approved for the treatment and management of bipolar disorder. These medications are specifically designed to help stabilize mood and address the symptoms associated with mood episodes in bipolar patients. This distinction underscores the primary use and classification of Haloperidol compared to the other options which are more directly involved in the management of bipolar disorder symptoms.