Here are some factors that make this question tricky:
* Official Language vs. National Language: Some countries have an "official language" which is used for government and legal purposes, while others have a "national language" which is more commonly spoken and considered a symbol of national identity. These might not always be the same.
* Multiple Official Languages: Many countries have multiple official languages, and English may be one of them alongside other languages.
* De facto Language: In some countries, English may be widely spoken and used even if it's not officially designated as a national language.
With those caveats in mind, here are some countries that are generally considered to have English as their national language:
Definitely:
* Antigua and Barbuda
* Australia
* Bahamas
* Barbados
* Belize
* Canada (along with French)
* Dominica
* Grenada
* Guyana
* Jamaica
* New Zealand
* Saint Kitts and Nevis
* Saint Lucia
* Saint Vincent and the Grenadines
* Trinidad and Tobago
* The United Kingdom
* The United States
Potentially:
* Ireland (English is an official language, but Irish Gaelic is also an official language and is considered the national language by some.)
* India (English is a scheduled language, and widely spoken, but Hindi is the national language.)
* Nigeria (English is the official language, but many other languages are spoken.)
* South Africa (English is one of the official languages, but others are also prominent.)
* Other Commonwealth countries: Some former British colonies have English as an official language but have other languages that are more prevalent in daily life.
It's important to note that this is not an exhaustive list, and the specific status of English in different countries can be complex.