When Star Trek: Voyager launched, its captain was named Elizabeth Janeway, after the American writer. That name was quickly changed to Nicole Janeway by Canadian actor Geneviève Bujold, who first played the part.
After just two days of filming, Bujold quit and producers pivoted to their second choice for the role: Kate Mulgrew, who again renamed the character—now to Kathryn Janeway—and proceeded to play the ship's captain from 1995 through 2001. (Mulgrew's most recent big TV role was as "Red" in Orange is the New Black.)
Because I wasn't paying much attention to Star Trek news in 1994, I never knew about this little casting mixup, though it's famous for serious Voyager fans. One enterprising (ahem, sorry) fan cut together several of the two Janeways' scenes from the pilot episode, so you can compare the two actors in the same role. Although the Bujold scenes lack music and other major production elements, it seems clear that Mulgrew was the right choice. Have a look: