Tessa Yeager is a character that appears in Transformers: Age of Extinction and (as a voice only) in Transformers: The Last Knight. She is the daughter of Cade Yeager and the girlfriend of Shane Dyson.
With only 2 weeks left of high school. Tessa found out that her dad has brought home an old vintage truck to strip down, much to Tessa's disapproval, she mostly tells her dad that he is wasting all the money on junk than completing the bills, and keeping the house. But Cade tells her that this truck can help her get to college.
After the argument, Tessa goes out with her friends, only to return and find out that her dad is hiding a Autobot in their barn. Tessa and Cade's friend, Lucas, tell Cade that if they call the CIA, they can get a lot of cash and pay for the house. But Cade ignores that and shorts the truck out. Much to Tessa's dismay, she goes and hides in the house.
A few moments later, Cade and Lucas finds a missile in the trucks engine and restarts it, causing it to fly out of the barn causing it to enter where Tessa is sitting. After this, she finds out that the truck has transformed into the Autobots leader Optimus Prime, who is severely injured from an ambush. Tessa then waits for Lucas to come back with the parts for Optimus.
Later, she sees a group of black cars coming towards the house. She automatically calls for her dad, after the men find out that Cade is keeping Optimus Prime, one of the men threatens to kill Tessa for details of Optimus's location, but Optimus breaks out and saves Tessa, Cade and Lucas. Then a car storms the area, drives right next to the three, telling them to get in. Tessa tells Cade that's her boyfriend Shane, but Cade is not happy about that.