Greg Mendell

Greg Mendell is a character on ABC's Once Upon a Time. He makes his debut in the eleventh episode of the second season. He is portrayed by Ethan Embry.

History
While Mr. Gold attempts to cross the Storybrooke border, Hook shoots Belle. This causes her to fall over the border and lose her memory. As Mr. Gold is about to kill Hook by use of magic, a car runs into Storybrooke and hits Hook before swerving into a tree. ("The Outsider")

Dr. Whale performs surgery on Greg and then Emma Swan visits him. She asks him what he saw and he tells her nothing, as he was looking down at his phone when the car got out of control. After she leaves, he calls someone who is presumably female and tells her he is okay and that she "won't believe what he saw". ("In the Name of the Brother")

Trivia

 * The casting call described him as "a major recurring guest star role with an option for next season [...]. A character named Barrett. He's in his 30s, kind and smart, but also has a very dark side and has beliefs and a way of life that he will fight fiercely to defend."
 * The character was originally referred to as Barrett, but that seems to have been a code name, as no "Barrett" is listed on the press release for "The Outsider".
 * Gregor Mendel was a monk who studied heredity and inheritance, and is posthumously regarded as the founder of genetic science.