Various is the correct author for any book with multiple unknown authors, and is acceptable for books with multiple known authors, especially if not all are known or the list is very long (over 50).
If an editor is known, however, Various is not necessary. List the name of the editor as the primary author (with role "editor"). Contributing authors' names follow it.
Note: WorldCat is an excellent resource for finding author information and contents of anthologies.
This eclectic assortment of old (mostly golden age) detective stories is the one recommended at the Crime Writers' Association open meeting at the time chaired by Simon Brett. It was mentioned in a review that I now can't recall but it was apparently the group's first choice when asked by a member of the audience for a good short story collection of golden age stories. I like to dip into my old copy, which are available quite cheaply on second hand book sellers websites. It has sometimes guided me to seek out books written by these sometimes forgotten authors.
This was my "Year Project". Trying to read 1 of the 50 short stories a week. Of course, this did not always happen, so it got to the next to last day of the year to finish it. The stories were a mixed bag. Some more engaging than others for me, but that's also personal preference for you. There were a lot of detectives I've never heard of before, and several I wouldn't mind reading more of - should my tbr pile allow for more books to be piled upon...