There is no site-wide standard in regard to American English versus British English. A best practice would be to follow what is primarily used in the country from which the article's subject originates. However, within articles maintain consistency by not switching back and forth between American and British English. If the country of origin for the article's subject either does not have English as an official language or uses a less common dialect of English, the default is British English for European countries, but otherwise use American English.