Alec Baldwin pursing his lips, squinting his eyes, saying “Jina.” Melissa McCarthy plowing a podium into a crowd of reporters. Kate McKinnon pivoting from a self-absorbed Hillary Clinton to a deer-in-the-headlights Kellyanne Conway.

As “Saturday Night Live” wraps up its 42nd season this weekend, these performances are destined for the history books: They helped the show achieve its highest ratings in two decades, and they helped define President Trump and his White House for liberals nationwide. For many on the right (and some on the left, too), Mr. Baldwin’s impersonation of Mr. Trump grew old fast, and some sketches crossed the line. But there’s no mistaking that the president, who attacked the show’s treatment of him, also turned it into appointment television again.

Here are some of the most talked-about sketches of the season, including a couple of favorites that have nothing to do with partisan politics.