Original music composed by Capcom (or other company):
• Manami Matsumae (Mega Man 1, Mega Man 2, and Mega Man 10)
• Yoshihiro Sakaguchi (Mega Man 1 and Mega Man 2)
• Takashi Tateishi (Mega Man 2)
• Yasuaki Fujita (Mega Man 3)
• Harumi Fujita (Mega Man 3)
• Makoto Tomozawa (Mega Man: Dr. Wily's Revenge [GB] and Mega Man 7)
• Minae Fujii (Mega Man 4)
• Kenji Yamazaki (Mega Man II [GB])
• Mari Yamaguchi (Mega Man 5)
• Jun'ya Ota (Cirno's Theme)
• Kouji Murata (Mega Man III [GB], Mega Man IV [GB], and Mega Man V [GB/SGB])
• Yūko Takehara (Mega Man 6 and Mega Man 7)
• Kinuyo Yamashita (Mega Man: The Wily Wars)
• Toshihiko Horiyama (Mega Man 7, Mega Man & Bass, and Mega Man Powered Up)
• Shusaku Uchiyama (Mega Man 8)
• Yoshinori Ono (Kaze yo Tsutaete)
• Naoshi Mizuta (Mega Man & Bass)
• Akari Kaida (Mega Man & Bass and Mega Man 10)
• Ryo Kawakami (Mega Man 9 and Mega Man 10)
• Yu Shimoda (Mega Man 9 and Mega Man 10)
• Ippo Yamada (Mega Man 9 and Mega Man 10)
• Hiroki Isogai (Mega Man 9 and Mega Man 10)
• Marika Suzuki (Mega Man 11)
• cityfires (30XX [Main Theme])
• Toby Fox (Undertale [MEGALOVANIA])
For Mega Man Maker only, either recreated, remixed, or even composed:
• Sapphire Sunsets (Mega Man: Dr. Wily's Revenge [GB], Mega Man II [GB], Mega Man III [GB], Mega Man V [GB/SGB], Mega Man: The Wily Wars, Mega Man 7, Mega Man 8, Kaze yo Tsutaete, Mega Man & Bass, Mega Man Powered Up, Mega Man Maker, and 30XX [Main Theme])
• CosmicGem (Mega Man 7, Mega Man 8, Mega Man Powered Up, Mega Man 9, Mega Man 10, Mega Man 11, and Mega Man Maker)
• RRThiel (Mega Man 7, Mega Man 8, Mega Man 10, Mega Man 11, and Mega Man Maker)
• POLARIA POYON (Mega Man 10, Mega Man 11, and Mega Man Maker)
• littlelamp100 (Mega Man 5 [Cirnosis Remix], Mega Man: The Wily Wars, Mega Man 7, Mega Man 8, Mega Man 10, Mega Man 11, and Mega Man Maker)
• MrKyurem (Mega Man Powered Up)
• ALUMOX (Mega Man II [GB], Mega Man V [GB/SGB], Mega Man: The Wily Wars, Mega Man 7, Mega Man 8, Mega Man & Bass, Mega Man 10 and Mega Man 11)
• MiniMacro (Mega Man: The Wily Wars, Mega Man 8, Mega Man 10, and Mega Man 11)
• GamerFromTheWeb (Mega Man: Dr. Wily's Revenge [GB], Mega Man II [GB], Mega Man IV [GB], Mega Man V [GB/SGB], and Mega Man & Bass)
• 40Nix (Mega Man: Dr. Wily's Revenge [GB], Mega Man II [GB], Mega Man III [GB], Mega Man V [GB/SGB], and Mega Man & Bass)
• Sophia (Mega Man & Bass)
• DeltaMudkip (Mega Man: Dr. Wily's Revenge [GB], Mega Man III [GB], Mega Man IV [GB], and Mega Man & Bass)
• Dr. "Radiation" Lumen (Undertale [MEGALOVANIA])
There we go...