Stan as many people know is a character in Eminem's popular song Stan. Because the character was so obsessive¹ the name can be used to describe an overzealous maniacal² fan for any celebrity³ or athlete.

大家都知道Stan是艾米纳姆的流行金曲《Stan》中的主人公。因为歌中的这个人物对艾米纳姆太痴迷，所以他的名字就被人们用来形容那些对名人或运动明星等过度病态痴迷的粉丝，即“铁杆粉丝”或者“狂热粉丝”。

You could call somebody a "stan" if you think they are obsessive of someone or something. It is formed from the words stalker and fan: stalker + fan = stan.

如果有人对某个人物或事物很痴迷，就可以称他为stan，这个词是由stalker（追随者）和fan（粉丝）这两个词组合而成的。