Offred's best friend in the novel is Moira. They have been close since college, long before the Republic of Gilead strips women of their rights and turns Offred into a Handmaid.
Moira is one of the novel's most openly defiant characters. At the Red Center, where the Aunts train and indoctrinate Handmaids, she escapes by stealing an Aunt's clothing and pass. Her rebellion gives Offred a powerful example of resistance, even though Offred's own response is more cautious and focused on survival.
Their paths cross again at Jezebel's, the secret club where Gilead's elite exploit women as prostitutes. Moira has been captured and chooses that assignment over being sent to the Colonies. The reunion is painful because it shows both her courage and the regime's ability to wear people down.
Luke is Offred's husband, Rita is a Martha in the Commander's household, and Janine is another Handmaid. They are important characters, but none is her best friend. The television adaptation also keeps Moira as June's closest friend while expanding her story.