Nintendo Gamecube USA Missing
From Redump Wiki
(Almost) all USA GameCube games that were sold normally in stores are believed to be dumped. Additional versions may exist (ex. version 1.00 vs. version 1.01). The most recent USA GameCube dump was added in 2014. Todo: crossreference with this list for discs / versions that are known to exist.
Official Games / Demos
Bomberman Generation 1.01 (info) Kiosk Demonstration Test Disc Release October 2001 (same as?)
Official Application Discs
Aging Test For Production. try59 (maybe there are other versions?) Read Check Program [DL-DOL-022E-JPN]
Properly dumping unlicensed discs is difficult, or perhaps impossible, depending on the disc and the technical skill of the end-user. For more information, see this thread on GC-forever.com.
There might be a disc for each version (1.00, 1.01, ... 1.20, if not more, because of 1.14a-1.14c). The following definitely exist, if scene releases are trustworthy.
Action Replay 1.06 Action Replay 1.08 Action Replay 1.09 Action Replay 1.14a Action Replay 1.14b Action Replay 1.14c Action Replay 1.18  Action Replay 1.20 (Works on all Wiis) (No code entry function) Action Replay Max
Produced by Datel. Some are called "Action Replay Ultimate Codes:", others are called "Ultimate Codes".
Action Replay Ultimate Codes MAX PACK: Mario Kart Double Dash, Mario Party 4 & 5, Mario Sunshine, Mario Golf Animal Crossing Enter The Matrix Final Fantasy - Crystal Chronicles Mario Kart - Double Dash!! Metal Gear Solid - The Twin Snakes (never released?) Metroid Prime The Legend Of Zelda - Twilight Princess The Legend of Zelda - The Wind Waker Wario World
Hopefully not updated as frequently as the Action Replay discs. The exact number of versions is not known.