pdffonts command line tool originally from Xpdf, now part of Poppler.
This tool is available in most Linux distributions as part of poppler-utils package.
Example usage and output:
$ pdffonts some.pdf
name type emb sub uni object ID
------------------------------------ ----------------- --- --- --- ---------
BAAAAA+Arial-Black TrueType yes yes yes 53 0
CAAAAA+Tahoma TrueType yes yes yes 28 0
DAAAAA+Wingdings-Regular TrueType yes yes yes 43 0
EAAAAA+Webdings TrueType yes yes yes 38 0
FAAAAA+Arial-BoldMT TrueType yes yes yes 33 0
GAAAAA+Tahoma-Bold TrueType yes yes yes 23 0
HAAAAA+OpenSymbol TrueType yes yes yes 48 0