VLC Media Player - VLC is a free and open source cross-platform multimedia player and framework.
Nightingale - Nightingale is a free and powerfull music player for Linux, Windows and Mac
SMPlayer - SMPlayer is a free video and audio player for both Windows and Linux that allows you to play almost all media files without having to install additional codecs. Read more about SMPlayer.
GNOME Music - Music is the new GNOME music playing application.
MPV - MPV is an audio and movie player based on MPlayer and mplayer2.
Roon (Music Player) - Roon is a music playing application for audiophiles