A group of crows is called a murder.
A group of crows is commonly referred to as a "murder". This term dates back to the 16th century, when it was believed that crows were capable of committing murder. The term is still used today, and is thought to be derived from an Old English word meaning "noisy crowd". Crows are highly social birds and can often be seen in large groups, which are known as "flocks" or "roosts".