The plural form of "passerby" is "passersby."
The plural form for the compound noun passer-by is passers-by.
passers-by
The noun 'passerby' is the singular form. The plural form is passersby.
The singular form is passerby; the plural for is passersby.
"Passerby" can be spelled alternatively as "passer-by," so, conceivably, you would want to say "passers'-by," though you may just want to find another noun to convey the same meaning without the confusion.
The passerby did not stop to speak with him. She waved to the passerby.
The possessive form for the noun passerby is passerby's.
The possessive form of the singular noun passerby is passerby's.example: That's a passerby's dog barking.
I saw a passerby help an elderly person cross the street.
The Passerby - 1913 was released on: USA: 10 November 1913
The cast of Zwillinge - 2010 includes: Cynthia Buchheim as Passerby Michael Hatzius as Bachelor Vivian Kanner as Passerby Vika Kirchenbauer as Bachelor Inga Kohler as Passerby Natalie Krane as Sofie Ingo Raabe as Bachelor Sebastian Schlecht as Passerby Madchen Unterwegs as Passerby Kai Zint as Bachelor