Who has won a Gold Medal in both the Summer Olympics and Winter Olympics?

Name the individual who has won a Summer Olympics Gold Medal and a Winter Olympics Gold Medal.

Also, name the years these Gold Medals were won, name the events in which these Gold Medals were won, and name which country the individual was representing.
Update: As the best answer lists the four individuals who have won medals at both the Winter and Summer Olympics, my question had to do with only one individual who won a Gold at the Summer Olympics and a Gold at the Winter Olympics who is Eddie Eagan and is listed properly in the "best answer".
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