1. Piper Chapman
Clare Foley is Piper as a child, and Taylor Schilling is her as an adult.
Jen Euston, the casting director for OITNB, talking about selecting children to play young versions of the show's characters with BuzzFeed News last year, said: "I only choose people who could realistically play them. Sometimes I have the [adult] actors send me pictures of them when they were little."
2. Tasha "Taystee" Jefferson
Teeka Duplessis plays Taystee as an 11-year-old, and Danielle Brooks is her as an adult.
"[Brooks] came in and had her hair back and everything but I knew she was the right one," Euston told BuzzFeed News. "I had her come back with her hair out like Taystee’s so she could look more like her, 'cause I could see it in her face."
3. Alex Vause
Rachel Resheff is Alex as a child, and Laura Prepon is her as an adult.
"For me, if their eyes and nose match up, then the rest can work," Euston said. "I usually have a picture of the person on my computer as I go through the pictures of the kids and just scan back and forth."
4. Suzanne "Crazy Eyes" Warren
Eden Wiggins plays Crazy Eyes as a 13-year-old, and Uzo Aduba plays her as an adult.
5. Nicky Nichols
Nicky is portrayed by Carla Oudin as a child and by Natasha Lyonne as an adult.
6. Carrie "Big Boo" Black
Big Boo is portrayed by Melanie Hinkle as a child and Lea DeLaria as an adult.
7. Cindy Hayes
Cindy is portrayed by Nyeema Carter as a child and Adrienne C. Moore as an adult.
8. Tiffany Doggett
Tiffany is portrayed by Oona Laurence as a child and Taryn Manning as an adult.
9. Norma Romano
Norma is portrayed by Kristin Parker as a teenager and Annie Golden as an adult.
10. Mei Chang
Chang is played by Teresa Ting as a teenager and Lori Tan Chinn as an adult.
11. Brook Soso
Brook is played by Ella Hampton as an 8-year-old and Kimiko Glenn as an adult.
12. Joe Caputo
Joe is portrayed by John D'Leo as a teenager and Nick Sandow as an adult.
13. Dayanara Diaz
Dayanara is played by Jheel Haldar as a child and Dascha Polanco as an adult.
14. Sam Healey
Sam is portrayed by Zachary Doran as a child and Michael Harney as an adult.
15. Sophia Burset
Pre-transition Sophia is played by M. Lamar. Present-day Sophia is played by Laverne Cox – Lamar's twin.
Emily Orley contributed to this report.