E. T. himself could look very frightening to many viewers. His design and voice don't help.
Though not overtly scary, the film has many moments that could be considered frightening and intense.
The opening scene is quite intense. E.T. is chased through the woods by government agents, screaming the entire way. Intense music plays throughout.
Elliot's first encounter with E.T. is a bit of a jump scare. Elliot is searching through corn stalks, following E.T.'s tracks. When he finally finds him, both scream at each other and E.T. runs away.
Elliot later waits in a lawn chair outside of his house's tool shed, knowing E. T. is inside. After falling asleep, Elliot hears shuffling and sees E. T. slowly coming out of the tool shed towards him. E. T. Continuously stops and then suddenly walks closer and closer but doesn't harm him.
After Elliot introduces E.T. to Michael, Gertie suddenly walks into the room and screams at the sight of the alien. E.T. screams in return, and pretty soon everyone is yelling.
The second half of the film is much darker and intense than the first half.
After being on Earth for too long, E.T. starts getting sick. He is found laying in a stream, half-dead and pale.