Fra Lippo Lippi is a 15th-century Carmelite monk and highly skilled Florentine painter. Orphaned as a toddler and driven by starvation, he joined the convent at age eight strictly for survival, receiving room and board in exchange for his religious vows. He possesses a strong appetite for sensual experiences and heavily resists the strict, idealized artistic conventions forced upon him by church leaders.

The Head Guard is a Florentine watchman conducting a sweep of the city's illicit districts. He initially detains the rogue monk but soon becomes a captive and sympathetic audience to the painter's long monologue. He is presented as a worldly man who understands human temptation.

Cosimo is an important politician and wealthy benefactor in Florence. He acts as Fra Lippo Lippi's patron, locking the painter in a room to force the completion of his religious artworks. He views art primarily as a mechanized commodity to bolster his own reputation.

The Prior is the leader of the Carmelite convent who recognizes Fra Lippo Lippi's artistic potential but demands idealized, emotionless religious art rather than realism. He maintains a hypocritical lifestyle, harboring a young woman he attempts to pass off as a family member.

Aunt Lapaccia is Fra Lippo Lippi's relative who briefly cares for him after he is orphaned. Overwhelmed by poverty and prone to physical violence, she eventually abandons the starving toddler at the local convent.

A young woman whom the Prior officially claims as his niece. Her highly realistic depiction in Fra Lippo Lippi's painting causes a panic for the Prior, leading him to order the artwork destroyed.

Tomasso Guidi is a young artist whom Fra Lippo Lippi views as the future of Florentine art. Lippo believes Guidi will carry on the revolution of realistic, sensual painting and successfully disregard the monks' aesthetic restrictions.

A visionary female figure Fra Lippo Lippi intends to include in his future religious painting. In his imagination, she steps forward to validate his artistic worth and defend his inclusion in the holy company.