Kim Kardashian may have been just a tad bit overdressed for this occasion. As the SKIMS founder revealed in an Oct. 30 Instagram Story, she attended Tracee Ellis Ross’ birthday dinner over the weekend wearing a striking Mystique costume for the event. But, as Kim noted, her choice of clothing may not have totally matched the theme. “That time I showed to a birthday dinner in full costume when it wasn’t a costume party!” Kim wrote alongside a photo of herself and the Hair Tales creator. “Happy Birthday to the most beautiful kind soul @traceeellisross.” However, it’s worth noting that she wasn’t the only family member getting all dressed up and into the spirit for the spooky festivities this year. In fact, just days before, Kim’s kids, North, 9, Saint, 6, Chicago, 4 and Psalm, 3, each channeled pop culture icons for their individual costumes. In an Oct. 28 Instagram post, Kim revealed that the four paid tribute to Aaliyah, Snoop Dogg, Sade Adu and Eazy-E respectively. But Kim isn’t the only star adding a little mystique to Halloween this year.