To the extent that "muggle" means "person unable to perform magic", then you're thinking of squibs; from [J.K. Rowling's old website][1]<sup>1</sup>

>A Squib is almost the opposite of a Muggle-born wizard: he or she is a non-magical person born to at least one magical parent. 

Argus Filch and Mrs. Figg are two examples of Squibs from the series.

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<sup>1</sup> Courtesy of the Wayback Machine

[1]:http://web.archive.org/web/20110721042840/http://www.jkrowling.com/textonly/en/extrastuff_view.cfm?id=19