Jesse D. Bright was a U.S. Senator for the state of Indiana during the U.S. Civil War. The U.S. Senate impeached and expelled him for being a sympathizer to the Confederacy. Making him the only expelled senator during the Civil War era to be from a northern state.
Constance Markievicz was an Irish politician who became the first woman elected to serve in British Parliament, but like many Irish people before and after her, she did not take her seat in House of Commons.
While he ran as Lincoln’s running mate (under a National Union party ticket), Andrew Johnson was not the greatest president after assuming the office upon Lincoln’s death. One such shameful note was him vetoing the 1866 Civil Rights Act. Luckily for African-Americans, Congress had enough votes to override his veto power.
While most Chief Justices of the Supreme Court never had to do so, but if a president is impeached, they preside over their trial in the Senate.
Bill Clinton was the first president to use email while in office, as well as having an inauguration streamed over the internet.