Toby is the dog belonging to the heroine Rennie Wickham and the tritagonist of Friday the 13th Part VIII: Jason Takes Manhattan. Toby was well loved by Rennie. He seems to have known both her teacher Colleen Van Deusen and her love interest Sean Robertson.
Toby and his owner Rennie Wickham were brought along, by Ms. Van Deusen so she could socialize more and enjoy her graduation. It didn't appear her uncle, Charles McCulloch one of the chaperones, was excited to have her or Toby on the cruise. Toby rarely left his owner's side and was her constant companion during the trip. Its not known if he could see her visions of a younger Jason who haunted her memories, but it was clear Toby would protect her if Jason tried to attack.
After Jason massacred, slaughtered, killed, and murdered the students and the staff, he caused the ship to sink. Toby, along a few surviving students, Ms. Van Deusen, Rennie herself, and her uncle escaped the sinking boat and Jason temporarily. But he would become separated from his owner when they reached New York. The group was jumped by two gang-bangers, who, after trying to mug them, tried to shoot Toby. Rennie got in between them and Toby fled from the gunshots. While what became of him wasn't known, he most likely wandered the streets looking for Rennie and the others. Jason didn't attack and kill Toby at all.
He's shown to have survived the entire ordeal and journeyed through New York at the end of the film. When Rennie and Sean had just escaped the flooding sewers and finally Jason, too, Toby came up from behind Sean on the streets above. The three were happily reunited and set off on their journey, free from Jason.