From TVTropes.org
Jeri Ryan divorced her husband to play Seven of Nine on Star Trek Voyager (he refused to move to Hollywood with her). The divorce was contentious, and a lot of salacious dirt was spilled. When Jack Ryan ran for the U.S. Senate in 2004, the release of the documents forced him to withdraw, allowing his challenger to win in a landslide against a last-ditch replacement. The landslide victory propelled the challenger, Barack Obama, to a position from which he could then launch a campaign for President, and... well, you know the rest.
It's not like she gave the office to him but it's an interesting butterfly effect.