If Indeed.com job search results are anything to go by there's also EBay, Verizon, Morgan Stanley, Northrup Grumman, Slack, Nike, JPMorgan.
Searching around the web I see other users including Netflix, Tumblr, Xerox, Sony, Siemens, UBS, Ask.com, AT&T, Bloomberg, IBM, Bank of America, Amazon, TomTom, NASA, Credit Suisse, Autodesk, Nokia, Apple, AOL, eHarmony, Gawker, HSBC, Klout, Novell, SAP, UBS, Allan Gray, Telefonica, Weather Channel, The Guardian.
Searching around the web I see other users including Netflix, Tumblr, Xerox, Sony, Siemens, UBS, Ask.com, AT&T, Bloomberg, IBM, Bank of America, Amazon, TomTom, NASA, Credit Suisse, Autodesk, Nokia, Apple, AOL, eHarmony, Gawker, HSBC, Klout, Novell, SAP, UBS, Allan Gray, Telefonica, Weather Channel, The Guardian.
https://www.quora.com/What-startups-or-tech-companies-are-us...
http://www.indeed.com/jobs?q=scala
https://www.quora.com/Any-companies-using-Scala-in-Berlin?sh...