Sayonara is a small, clear and fast audio player for Linux written in C++, supported by the Qt framework. It uses GStreamer as audio backend.
Pamuter Media Klasik
Media Player Classic Home Cinema (mpc-hc) is considered by many to be the quintessential media player for the Windows desktop. Media Player Classic Qute Theater (mpc-qt) aims to reproduce most of the interface and functionality of mpc-hc while using libmpv to play video instead of DirectShow.
Gnome Connections
A remote desktop client for the GNOME desktop environment
QMPlay2
QMPlay2 is a video and audio player. It can play all formats supported by FFmpeg, libmodplug (including J2B and SFX). It also supports Audio CD, raw files, Rayman 2 music and chiptunes. It contains YouTube and MyFreeMP3 browser.
Wayang Monad
Movie Monad is a free and simple to use video player made with Haskell.
kafein
Kaffeine is a media player. What makes it different from the others is its excellent support of digital TV (DVB). Kaffeine has user-friendly interface, so that even first time users can start immediately playing their movies: from DVD (including DVD menus, titles, chapters, etc.), VCD, or a file.
Haruna
Haruna is an open source video player built with Qt/QML on top of libmpv.
Pragha
Pragha is a Lightweight Music Player for GNU/Linux, based on Gtk, sqlite, and completely written in C, constructed to be fast, light, and simultaneously tries to be complete without obstructing the daily work. 😉
Videos
Also known as Totem, Videos is a movie player designed for GNOME.
GMusicBrowser
A customizable open-source jukebox for large collections