Adiós - another version of "goodbye", similar to "hasta luego".
Chao - short for "chau chau", is used in informal settings and is commonly heard among young people.
Nos vemos - (literally "see you") is a way to say goodbye to someone you expect to see again soon, such as a friend or colleague.
Que te vaya bien - (literally "may it go well for you") is a polite way to say goodbye and wish someone well.
Me voy - (literally "I'm going") is a simple way to say goodbye and let someone know you're leaving.
Cuídate - (literally "take care of yourself") is a friendly way to say goodbye and express your concern for someone's well-being.
Hasta la próxima - (literally "until next time") is a way to say goodbye to someone you expect to see again in the future.
Buenas noches - (literally "good night") is used to say goodbye when parting ways in the evening.