Final answer:
The musical not composed by Stephen Sondheim is 'Wicked,' which was actually composed by Stephen Schwartz. Sondheim is renowned for his contributions to other acclaimed musicals, but not this one.
Step-by-step explanation:
The musical Wicked was NOT composed by Stephen Sondheim. While Sondheim did compose 'Sunday in the Park with George,' 'Into the Woods,' and 'Sweeney Todd,' he did not compose 'Wicked.' That honor goes to Stephen Schwartz. Stephen Sondheim is widely regarded as one of the most important figures in musical theater, known for his clever lyrics, complex music, and the depth he brought to storytelling in musicals. 'Wicked,' on the other hand, is a modern musical that has captivated audiences with its reimagined story of the witches from 'The Wizard of Oz.'