This week's most sought after party guest was also the most elusive one. On Thursday evening, Justin Bieber attended a party to celebrate his stylist Karla Welch's new collaboration with Hanes t-shirts. Or, so the press release said. Bieber, who has been making quite a few headlines this week thanks to his world tour cancellation and that whole accidentally hitting a paparazzi with his car, opted not to get his photo taken at the event, as is celebrities are wont to do at these kind of events. His presence still loomed over the event, also attended by birthday girl Karlie Kloss, as images from the campaign starring the singer hung from the walls. Also this week, the Hamptons continued to be popular as ever, as Jessica and Jerry Seinfeld attended the GOOD+ Foundation's Hamptons Summer Dinner, co-hosted by Net-A-Porter, and both Ashley Benson and Tiffany Trump attended an Assouline dinner held at the Surf Lodge. Here, a look at all of the party pictures that you may have missed this week.

Karla Welch and Soko attend the x karla Launch Party.

Stefanie Keenan

Stylist Karla Welch feted her new clothing line, while Soko played DJ for the evening.

Tracee Ellis Ross attends the x karla Launch Party.

Stefanie Keenan

Also in attendance was Welch's always stylish client, Tracee Ellis Ross.

Zoe Saldana and Marco Perego attend the Avant Garden Gala at Lotusland in Santa Barbara.

Zoe Saldana, along with husband Marco Perego, welcomed the end of summer at the Avant Garden Gala at Lotusland in Santa Barbara, presented by Valentino.

The Seinfeld family attends NET-A-PORTER Co-Hosts The GOOD+ Foundation's Hamptons Summer Dinner.

Bryan Bedder

Sascha, Jessica, and Jerry Seinfeld made the GOOD+ Foundation's Hamptons Summer Dinner, co-hosted by Net-A-Porter a family affair.

Ashley Benson attends the Assouline dinner for ibiza Bohemia.

Madison McGaw/BFA.com

Also in the Hamptons, Pretty Little Liars star Ashley Benson attended a dinner for Ibiza Bohemia far from Spain at the Surf Lodge.

Tiffany Trump attends an Assouline dinner for ibiza Bohemia.

Madison McGaw/BFA.com

Tiffany Trump also made an appearance at the dinner, held at Montauk hot spot, which frequent flunkie Andrew Warren reportedly fractured his arm in a self-described "botched act of heroism."

Alex Sharp and Alex Carleton celebrate the Filson Partnership with the United States Forest Service and National Forest Foundation.

Back in New York, Broadway star Alex Sharp came out to celebrate the Filson Partnership with the United States Forest Service and National Forest Foundation, alongside Filson creative director Alex Carleton.

The cast of Fun Mom Dinner attends Momentum Pictures With The Cinema Society & SVEDKA Host A Screening Of "Fun Mom Dinner".

Jim Spellman

Katie Aselton, Toni Collette, Bridget Everett, and Molly Shannon celebrated their new film Fun Mom Dinner at a screening hosted by the Cinema Society & Svedka.

Jeremy Renner and Elizabeth Olsen attend The Weinstein Company With FIJI, Grey Goose, Lexus And NetJets Host A Screening Of "Wind River".

Paul Zimmerman

And Avengers co-stars Jeremy Renner and Elizabeth Olsen reunited for the premiere of their film Wind River.

Related: Did Justin Bieber Cancel His Tour to Dedicate Himself to God, or Just to "Ride Some Bikes"?

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