Gallbladder: This small organ stores bile produced by the liver. People can live without it, often having it removed due to gallstones.
Appendix: Once thought to be a vestigial organ, the appendix is now believed to play a role in gut immunity.
One Kidney: Humans have two kidneys, but can live a normal life with just one. People often donate one kidney and live healthily, as the remaining kidney compensates for the loss of the other.
Spleen: This organ helps filter blood and is part of the immune system. Its removal (splenectomy) is sometimes necessary due to diseases or injury.
Part of the Liver: The liver has an incredible ability to regenerate. A significant portion of the liver can be removed (as in the case of a liver donation), and it can regrow to its full size while maintaining its functions.
Stomach: In some cases of cancer or severe ulcers, part or all of the stomach may be removed.
Reproductive Organs: Hysterectomy (removal of the uterus) and oophorectomy (removal of the ovaries) in females, or orchiectomy (removal of the testes) in males, can be done without affecting survival.