An ensign is a national flag when used at sea, in vexillology, or a distinguishing token, emblem, or badge, such as a symbol of office in heraldry. The word has also given rise to the military rank of "ensign", a rank of junior officer once responsible for bearing the ensign.

The word is derived from the Latin plural insignia.

In nautical use, the ensign is flown at the stern of a ship or boat to indicate its nationality. Ensigns may also be flown from the gaff of a ship, and may be shifted to a yardarm when the ship is under way, where it is known as a steaming ensign. Vexillologists distinguish three varieties of a national flag when used as an ensign:

Many countries do not distinguish between these uses, and employ only one national flag and ensign in all cases. Others (like the United Kingdom, Italy, Russia, South Africa, Australia, New Zealand, and Japan) use different ensigns. Such ensigns are strictly regulated and indicate if the boat is a warship, a merchant vessel or a yacht, for example.

Sean Ensign is an American singer-songwriter, born in 1972, in Cleveland, Ohio.

The last of eight children, Sean Ensign was raised in Cleveland, Ohio. From an early age, he learned to appreciate the value and beauty of music. Ensign taught himself to play the piano. He took every chance that presented itself to sing. However, it was not until he began writing his own songs that he was able to fully express himself emotionally and artistically. Before releasing his first album, Ensign worked as a professional hospital intensive care nurse and as a male model.

Ensign started on the road to becoming a successful singer and songwriter after being signed to the label, Titan Sounds. He soon began to make waves in the music world, particularly, the Club/Dance music industry. His debut single, "It's My Life (Finally)" peaked at #35 on the Hot Dance Music/Club Play and #21 on the Hot Dance Singles Sales chart. The follow-up single, "Without You" saw greater success peaking at #4 on the Hot Dance Music/Club Play. Both songs are from his debut album, Finally which blends Hi-NRG music songs with passionate ballads. He also covered the Ace of Base song, "Everytime It Rains." Ensign's third single "Everytime It Rains" is in the works with an acustic ballad version and many Club/Dance remixes done by other producers including Hex Hector for the CD single. The remixes are being sent to DJs and clubs in both Europe and the United States.