With biblatex you would use @suppbook or @inbook. @suppbook is explained by the biblatex documentation as
Supplemental material in a @book.
This type is closely related to the @inbook entry type.
While @inbook is primarily intended for a part of a book with its own title
(e.g., a single essay in a collection of essays by the same author),
this type is provided for elements such as prefaces, introductions,
forewords, afterwords, etc.
which often have a generic title only.
Style guides may require such items to be formatted differently
from other @inbook items.
The standard styles will treat this entry type as an alias for @inbook.
There is, in fact, one (and only one) difference in the output between @suppbook and @inbook in the biblatex standard styles: The title of @inbook is wrapped in quotation marks, whereas the title of @suppbook is unformatted.
\documentclass[british]{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{babel}
\usepackage{csquotes}
\usepackage[style=authoryear, backend=biber]{biblatex}
\usepackage{filecontents}
\begin{filecontents}{\jobname.bib}
@suppbook{jones:suppbook,
author = {Gwyneth Jones},
title = {Introduction},
bookauthor = {Joanna Russ},
booktitle = {The Female Man},
publisher = {Gollancz},
series = {SF Masterworks},
year = {2010},
pages = {ix--xii},
}
@inbook{yones:inbook,
author = {Gwyneth Yones},
title = {Introduction},
bookauthor = {Joanna Russ},
booktitle = {The Female Man},
publisher = {Gollancz},
series = {SF Masterworks},
year = {2011},
pages = {ix--xii},
}
\end{filecontents}
\addbibresource{\jobname.bib}
\begin{document}
\cite{jones:suppbook,yones:inbook}
\printbibliography
\end{document}

If you are not using biblatex, but classical BibTeX, there is no obvious good type available for entries like this. Note however, that there are some differences between individual .bst styles, the discussion here mainly focusses on the 'standard styles' plain.bst and friends and the 'standard' fields and types as discussed in the BibTeX documentation on CTAN.
@inbook would probably be the first choice, but it usually doesn't have the booktitle biblatex has, so you would give the title of the book in title and would have to give the chapter title in chapter, furthermore you can't have two authors.
@incollection has the obvious disadvantage that the author of the book could only be given as editor, which would not be accurate. Since something like "ed." would appear in the output, this is a no-go.
So you will have to resort to some creative abuse of fields.
As btxdoc says
The standard style’s thirteen entry types do reasonably well at formatting most entries, but no scheme with just thirteen formats can do everything perfectly.
Thus, you should feel free to be creative in how you use these entry types (but if you have to be too creative, there’s a good chance you’re using the wrong entry type).
Don’t take the field names too seriously. Sometimes, for instance, you might have to include the publisher’s address along with the publisher’s name in the publisher field, rather than putting it in the address field.
Or sometimes, difficult entries work best when you make judicious use of the note field.
For example
\documentclass[british]{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{babel}
\usepackage{csquotes}
\usepackage{filecontents}
\begin{filecontents}{\jobname.bib}
@inbook{jones:inbook,
author = {Gwyneth Jones},
chapter = {Introduction},
title = {\textup{In Joanna Russ:} The Female Man},
publisher = {Gollancz},
series = {SF Masterworks},
pages = {ix--xii},
}
@misc{jones:misc,
author = {Gwyneth Jones},
title = {Introduction},
note = {\textup{In Joanna Russ:}
\emph{The Female Man.}
SF Masterworks.
Gollancz, 2010,
pp.~ix--xii},
publisher = {Gollancz},
series = {SF Masterworks},
year = {2010},
pages = {ix--xii},
}
\end{filecontents}
\begin{document}
\nocite{*}
\bibliographystyle{plain}
\bibliography{\jobname}
\end{document}
That isn't pretty, but it produces usable output here.
What exactly works will also depend on the bibliography style you use and what you expect.
biblatexyou could use@suppbook(or@inbook), but I guess with most BibTeX styles you are out of luck. You could try moving the field contents around a bit and abusing field contents, but what works will definitely depend on the style you use. – moewe Jun 25 '19 at 10:28