an anthropomorphic pink dog in a jester halloween costume does die in the mysterious house, but it’s never shown, only its mutilated body appears and you can barely even notice it’s a dog
While no character is explicitly being stalked, there is the implication that the "killer" character of the series is looking for/hunting our main character.
A woman is killed in a gruesome and violent manner by what is heavily implied to be her husband, but the circumstances are such that it's difficult to say whether or not this counts.
Tricky, as the main villain is the protagonist's father and he definitely intends to hurt her once he finds her, but circumstances make it difficult to say whether it's really abuse, and it's stated that the main villain was a decent father in life. Also, in the Halloween special, a pair of children die horribly.
You might because of how many flashing lights there are <//3
actually tho there are no characters that have a seizure but the spasming of the robots can look similar to someone seizing