Back for her third time as host of "Saturday Night Live," Scarlett Johansson helmed a low-key episode of the sketch-comedy favorite.

Dressed in a dark suit, Johansson conceded in her opening monologue that she's not promoting anything in particular and has been staying out of the spotlight. Then she doled out tips to other celebs eager to keep their business out of the tabloids, such as always wearing underwear, avoiding reality shows and keeping a cool head when a sex tape leaks. Kristen Wiig as Dina Lohan and Abby Elliott as a Ke$ha joined the actress for a rendition of "Class" from the musical "Chicago."

Johansson popped up in a faux TV spot for "Maternity Television," a baby-friendly version of MTV, featuring shows like "America's Next Pregnant Dance Crew," "I'm Snooki and Pregnant" and "Cribs," which simply focused on beds for babies.

The "Iron Man" star also played a super-brash version of Patti Stanger, the host of Bravo's "Millionaire Matchmaker," who is tasked with setting up a dowdy lawyer with a penchant for beefy prospects. She also got her shimmy on as a guest on pretend Dominican broadcast "The Manuel Ortiz Show," as a woman trying to determine the father of her child, and played a child star embroiled in a local theater rivalry with another tween actress who both deliver inappropriately upbeat versions of powerful monologues from films like "The Color Purple" and "On the Waterfront."

The show's topical sketches included a spoof of the box-office hit "Unstoppable" with Johansson relaying terrible news as Jay Pharoah's Denzel Washington tries to halt the runaway train, including the fact the children on the train are carrying souvenirs from their field trip to a petroleum factory.

Pharoah returned to "Weekend Update" as Kanye West alongside Jason Sudeikis' version of President George W. Bush, insisting [article id="1651979"]they had squashed their beef[/article].

"We're both rich and we're both impulsive. He interrupted Taylor Swift at an awards show, I interrupted how well our country was doing for eight years," Sudeikis quipped about the pair's similarities.

Musical guests Arcade Fire turned out two impassioned performances, the first helmed by Win Butler for "We Used to Wait." The energy built up throughout the song, with Butler jumping into the audience and picking up the mic stand during peaks of the set, wrapping up the performance by belting directly into the camera.

Régine Chassagne busted out a sparkly sequined frock while the instrumentalists donned suits adorned with flickering neon lights when the band returned for "Sprawl II."

Chassagne gently crooned the lyrics but kicked up the energy for the bridge where she twirled about, whipping around two bunches of ribbons while the collective jammed on their respective instruments.

What did you think of "Saturday Night Live"? Let us know in the comments!