Dr. Caballeron's henchponies

Biff, Rogue, Withers, and Rosy Thorn are four ponies who have appeared in Daring Don't and/or chapter books as henchponies to Dr. Caballeron. Biff, Rogue, and Withers are unnamed in the show, but they are named in chapter books, and Biff is also named in merchandise.

Depiction in the series
Biff, Rogue, and Withers appear in the season four episode Daring Don't. They are first seen invading Daring Do's forest home and fighting her for the Ring of Destiny. When Rainbow Dash accidentally distracts Daring Do, the henchponies overpower her, and Dr. Caballeron seizes the Ring of Destiny from her.

When Caballeron and the henchponies are later approached by Daring Do in disguise, they prepare to sell the Ring of Destiny to her for a large amount of bits, but Ahuizotl arrives and scares them off.

Chapter books
In the chapter book Daring Do and the Eternal Flower, Outlaw (implied to be Biff but unidentified), Rogue, and Withers appear again as Dr. Caballeron's henchponies. They ambush Daring Do at a dinner party hosted by the Equestrian Botanical Society, but she eventually overcomes them. Later, she meets Caballeron's fourth henchpony: a freelance adventurer Pegasus named Rosy Thorn.

Rosy Thorn briefly teams up with Daring Do to rescue Daring's uncle Gallant True from Ahuizotl. However, she is later revealed to be one of Ahuizotl's partners, and she betrays Daring in order to get her to lead them to the Eternal Flower.

Withers appears again in Daring Do and the Forbidden City of Clouds. He breaks into A. B. Ravenhoof's house in search of information about Cirrostrata, an invisible city in the sky.

Merchandise
In the Crystal Games expansion set of Enterplay's collectible card game, Biff is named on card #156 R, which attributes to him and Daring Do the respective quotes "Running away, Daring Do? What are you, chicken?" and "Nopony calls me chicken..."

Quotes
"Well, not anymore! I was strapped for cash and he needed extra ponies. It was just a job! But I want to help you!"

- Rosy Thorn, Daring Do and the Eternal Flower

"I just thought it would be interesting to hear more about this thing that everypony wants so badly. Must be pretty special."

- Rosy Thorn, Daring Do and the Eternal Flower

"I told you she'd say that. Maybe I can convince them to help us. After all, we're old friends...."

- Rosy Thorn, Daring Do and the Eternal Flower

"If you're thinking about escaping—don't. You've seen me in action. I'm fast enough to catch you."

- Rosy Thorn, Daring Do and the Eternal Flower

"Running away, Daring Do? What are you, chicken?"

- Biff, Enterplay collectible card game The Crystal Games card #156 R of Biff