Is themself a pronoun

The Word 'themself' is used informally when the gender of a person is unknown. The reflexive/intensive pronoun is themselves, because the personal pronoun 'them' is the plural form.

The more appropriate pronoun to use when the gender is unknown or could be either male or female are 'they' and 'them', as a pronoun for people in general; or the more awkward he/she.