From Sonic Retro
December 20 (
- 1971 — Michael Yurchak, the English voice of Jet the Hawk since 2010, is born.
- 2001 — Sonic Advance is released for the Game Boy Advance in Japan. Sonic Adventure 2: Battle is released for the Nintendo GameCube in Japan.
- 2005 — Sonic the Hedgehog Mobile is released for J2ME compatible phones in North America.
- 2006 — Volume 2 of Sonic the Hedgehog Archives, a trade paperback, is released in North America.
- 2011 — Sonic the Hedgehog CD is released for the PlayStation 3 in North America.
- 2013 — Happy Sonic! Live Wallpaper is released for Android devices in Japan, North America, and Europe.
- 2018 — "From: A. Rose", a special holiday episode of Sonic Mania Adventures, is released on YouTube.