Here’s how some of them have shaped the events that have unfolded so far.

Representative Elise M. Stefanik, upstate: Before last week, this third-term Republican from upstate was best known for being the youngest woman elected to Congress. ( That title now goes to her Democratic counterpart Representative Alexandria Ocasio-Cortez ).

Now, Ms. Stefanik is earning fame for something else. She accused the Democrat leading the inquiry, Representative Adam Schiff of California, of trying to silence her and other members of her party “simply because we are Republicans.”

As a result of Ms. Stefanik’s performance during last week’s hearings, President Trump called her “a new Republican star” on Twitter. She embraced the comment and criticized the “Radical Left” for “their sick attacks on me.”

Ms. Stefanik’s newfound celebrity has earned her hundreds of thousands of new followers on Twitter.

[A G.O.P. star emerges in impeachment hearings.]