QuiteRSS [http://quiterss.org/]
KDE Kontact [https://userbase.kde.org/Kontact]
Liferea [http://lzone.de/liferea/]
RSS Guard [https://github.com/martinrotter/rssguard]
Seamonkey [http://www.seamonkey-project.org/]
Thunderbird [https://www.mozilla.org/en-US/thunderbird/]
Firefox ("live bookmarks") [https://www.mozilla.org/en-US/firefox/products/]
In the console, I like newsbeuter [http://www.newsbeuter.org/]
(I do need to set some filters on my Gmail so they don't appear in the INBOX, though)
https://jangernert.github.io/FeedReader/
I'm sure there must be others out there for Linux? There are several available for OS X (er, macOS); I use a commercial one called Reeder, but there's also NetNewsWire and the open source ViennaRSS (which appears to still be in active development).
iTunes supports RSS if you're on Mac or Windows though it's not obvious (File->Subscribe to podcast... add RSS link)