The Most Irreplaceable CEOs in the World By Ready To Startup  [26 more lists]

NOTE: This list is just for CURRENT CEOs. It is not intended as an "All-Time Greatest CEOs" collection. Please only include executives currently holding the chief executive position in a company. In January of 2012 Yahoo co-founder Jerry Yang resigned from the company’s board of directors and from all other positions with the company and in August of 2011, Apple founder and CEO Steve Jobs announced he would be resigning from his position (though he remained on board as an Apple employee and board member until his death). Though Jobs was replaced by the capable Tim Cook, this still sparked a lot of discussion about the fate of Apple after the loss of its long-time leader and chief innovator and the same can be said of Yahoo.

This list identifies the other Chief Executive Officers who are centrally important to their companies, and whose departure would lead to concerns about the fate of the business as a whole. They needn't be from the world of technology, either. Any CEOs of any major companies are eligible for consideration.

And because this is an Open List, add the names of any irreplaceable CEOs you think companies could not prosper without. They'll get added to the main list and then the Ranker community can vote on the Most Essential CEOs.