Admetus is a young king who enjoys hosting parties with his beautiful wife, Alcestis. His famous hospitality has earned him Apollo's friendship, and the god has arranged that he can avoid death if someone agrees to die in his place. When a fatal illness strikes Admetus, the only person willing to die in his place is his wife. In his bereavement Admetus realizes he should not have allowed Alcestis to die in his place. She was his only true friend. As soon as he acknowledges his role in her death, however, the couple is reunited. Heracles—a grateful recipient of Admetus's hospitality—has fought Death and rescued Alcestis.
Although she is the titular character, Alcestis speaks in only one episode and then dies before the scene ends. A deeply loving wife, Alcestis is Admetus's only true friend. When no one else will die to save her husband's life, she willingly takes his place. She blames Admetus's aged parents for choosing the few years they have left over saving their son. She never blames Admetus himself for allowing her to die in his place. She uses her last hours to prepare herself for burial, thus sparing her husband that pain. After her death, Alcestis is continually present in the hearts and minds of those she has left behind. In the final moments of the play, she returns to life and to the stage, but she has no lines. Despite her brief interaction with the other characters, Alcestis has a dominant influence on the plot.
Heracles serves two purposes in the play. His famous slow-wittedness, drunken antics, and love of practical jokes provide comic relief. At the same time, his heroism saves the day for his host, Admetus. As one of Greek mythology's greatest heroes, Heracles considers it a routine feat to tackle Death and wrest Alcestis from his grasp. It is so routine he turns his daring exploit into a practical joke. In the Exodos he returns Alcestis to Admetus by pretending he she is a nameless young woman he has won in an athletic contest.
The chorus is integral to the action of the play. It interacts with Admetus and other characters, providing insight into offstage events. It provides the audience with an idea of how the people of Pherae view the life and troubles of the king and queen. It also reminds the audience of the mythology behind the events of the play.