Slash (debut; 2 Episodes)
“Supporting” · Season 2
Tang Shen (photographs/flashbacks; 8 Episodes)
Dr. Kirby O'Neil (7 Episodes)
Mrs. O'Neil (photograph; "The Kraang Conspiracy")
Timothy/the Pulverizer ("Mutagen Man Unleashed")
Dr. Falco/the Rat King ("Of Rats and Men")
Ivan Steranko
Anton Zeck
These quotes come from Wikiquote's Teenage Mutant Ninja Turtles (2012) pages and are available under the Creative Commons Attribution-ShareAlike License.