This stalker doesn’t get an official name in the anime except for Unhinged Fan.

Unhinged Fan (Aggretsuko)

Jigglypuff appears on throughout the early years of the anime. It’s funny but creepy.

Jigglypuff (Pokemon)

She fell in love with Yuki and so she traveled to a new universe to get him.

Yuno (Future Diary)

The creepiest part about his murder spree is his love of female hands which he keeps as trophies.

Yoshikage (Jojo’s Bizarre Adventure)

Yoshikage (Jojo’s Bizarre Adventure)

Knives appears off and on to make Vash’s life a living hell either in person.

Knives (Trigun)

He is being friendly while other times he appears to create chaos through player killing.

Sora (hack//Sign)

People around the school have reported him stalking others which sounds suspicious.

Mitsuo Kubo (Persona 4)

He is hunting heroes who he doesn’t think deserve their jobs.

Toga (My Hero Academia)