WASHINGTON — Hope Hicks, the White House communications director who worked behind the scenes to direct the president through multiple professional crises — and decided to resign after she found herself exhausted by them — has left the building.

Those left behind are wondering what happens now.

Thursday was the last day at the White House for Ms. Hicks, a 29-year-old from Connecticut, whose unlikely career trajectory from corporate public relations hand to White House communications director kept pace with President Trump’s own unorthodox rise to the Oval Office. Over three and a half years, from the early trenches of the presidential campaign to desks within earshot of each other in the West Wing, Ms. Hicks had become Mr. Trump’s most trusted aide — and, perhaps most important, his unofficial translator to the rest of the staff.

“Her ability to anticipate what he wants and also execute can’t be replicated,” said Hogan Gidley, a White House spokesman. “At least not immediately.”

Ms. Hicks never gave a single on-camera interview during her time in the White House. Unlike her boss, attention from the news media was never something she sought.