Sierra is a human character.


Sierra first appeared in the special Rosie, Caroline, and the Christmas Party, which takes place between Saving Benjamin and Rosie, Jacob, Sierra, and the Troublesome Trucks. In this special, she, along with Jacob, Cassie, and Caroline, came to Sodor for the first time to visit Kira and her family. Sometime between the special and Rosie, Jacob, Sierra, and the Troublesome Trucks, Jacob and Sierra decided to stay on Sodor.

Later in the first season, Sierra and Jacob convinced Sir Topham Hatt to restore Glynn and they threw surprise birthday parties for Cassie and Caroline.

In the ninth season, Jacob and Sierra were left in charge of the North Western Railway while Richard Hatt's family went on holiday, much to the dismay of Marie and Rose.


Sierra is a very loving and caring girl. She is also determined and very persistent.


Sierra can almost always be found wearing either yellow or purple.


"What's wrong guys?"
"Oh, nothing. We're just a little homesick."
"But, Ms. Sierra, how could you be sick of a wonderful place like Sodor?"
"No, Toad homesick means that we miss our home, not that we're sick of yours."
"Oh, sorry, Mr. Jacob."
"That's alright, Toad. After, all you gave us a good laugh.
Duck, Sierra, Jacob, and Toad, Homesick, season 1

"I don't think it's very wise of Mr. Hatt to leave those two immature children in charge of us."
"They're not children anymore, Marie. They're 16 now."
"And anyway, they've been on Sodor, taking care of themselves for like 3 years now. I think if they can take care of themselves for that long, then they can certainly take care of all of us for a week."
"They're still young, and they surely aren't responsible enough to take care of a railway as big as this one."
"I hate to admit it but, Marie’s right. This railway should not be left in the hand of two incompetent and irresponsible children.
— Marie, Rosie, Madison, and Rose about Jacob and Sierra, The Substitute Controller, Season 9


  • Sierra is one of only two characters to be the main character in at least one episode in every season, with the other being Jacob.
  • Jacobacranmer, Sierra's creator, based her on his best friend.