If you mean what placements and aspects can make a native more prone to ~people stalking them: from my personal experience, Scorpio Ascendant with Pluto in the first house. I feel like it depends on synastry too: whether the stalker has conjunctions to any of the native's personal planets. Some synastry placements and aspects can really invoke obsessive vibes from people - like some sort of spell has been put on them.
Here are some links I found on this topic, whether that be natal charts that attract stalkers, or natal charts of people with obsessive tendencies that lead to stalking:
I read Pluto conjunct Ascendant is one of the main aspects that attracts people with obsessive and stalker tendencies. I also Noticed celebrities with Ascendant Conjunct Pluto have Obsessive fan bases Justin Bieber Benedict Cumberbatch Beyonce Leonardo DiCaprio Also the late actress...
If you mean for someone to be a stalker - if they have a fallen/detr. ASC ruler in 7th house, especially Mars (fighting to win over), or Saturn (desire to control). Especially if it's Mars in Taurus or Saturn in Leo (fixed signs) - forget about it!
Add to it a Virgo/Capricorn/Aries/Scorpio Moon, especially if it's beaten.
As an extra point - Lilith conjunct ASC. You'll get a nasty stalker.