Sunkist

Sunkist is Tommy's pet dog, a massive golden retriever genetically engineered within Black Mesa as a bioweapon of sorts, and is introduced in Act 4, where it is held hostage by Forzen and threatened with a circle of armed turrets. Sunkist later returns to join the crew during the final boss fight against Benrey. Sunkist is played by Lauren.

Sunkist is shown to be immortal and capable of supernatural abilities, such as levitation, utilizing the Black Mesa Sweet Voice, and an immunity to pain or damage to its body. Being immortal allows him to be rapidly shot by turrets with no reaction, ultimately ruining Forzen's plans to kill him.

Trivia

 * Sunkist has the shadow of a human.
 * Sunkist is likely based off of Cossette's Dog from Ace Combat 7, which is commonly known as the "JPEG Dog" for being a 2D image of a dog during one of the game's cutscenes.