Which European country has a national flag with a red field and a white crescent and star? Turkey. Its national flag is a red field bearing a white crescent and five-pointed star, placed slightly left of center.
The design developed from Ottoman flags. The star and crescent appeared on Ottoman flags by the late 18th or early 19th century, and the red version was adopted in 1844 during the Tanzimat period. When the Republic of Turkey was established in 1923, it retained the design.
Turkey’s Flag Law standardized the flag’s proportions and precise design in 1936; a later law in 1983 further defined its specifications. The flag is commonly called Ay Yıldız, meaning “moon-star,” and Al Bayrak, meaning “red flag.”
A common mix-up is with other flags using a crescent and star, such as those of Pakistan, Tunisia, or Azerbaijan. However, among the listed European countries, Turkey is the single canonical answer.