A vigil (from the Latin vigilia, 'wakefulness') is a period of sleeplessness, an occasion for devotional watching or observance. It could be a watch kept during normal sleeping hours as a period of observation or surveillance. It can also be the eve of a religious festival observed by staying awake as a devotional exercise or ritual devotions observed on the eve of a holy day, such as the Easter Vigil held on Holy Saturday.

It is also part of the title of a poem by Walt Whitman, "Vigil Strange I Kept on the Field One Night".

It is also the title of a film (1984) by New Zealand director Vincent Ward.