WARNING: This article contains major spoilers from "It's a Super Life," the 100th episode of Supergirl.
When Mr. Mxyzptlk returned for Supergirl's 100th episode, he looked very different -- but there's a good reason for that.
In "It's a Super Life," Mxyzptlk returned from the fifth dimension. At first, Kara and Alex didn't believe it was him. However, he proved he was who he said he was by using magic to show them a flashback to his previous self. "Okay, I only took on that other form and sophisticated accent to impress you," he explained, not the least bit sheepish. "But it worked! You caught me."
"Ugh, I miss that hair. I really, really do," he added, watching the footage of his previous self. Then, he revealed his new, improved agenda: "But now, I can't use any of my powers, except to help those whom I have wronged" -- and Kara was the last name on his list.
To fulfill his duty to right his wrongs, he offered Kara a chance to go back in time and confess her secret identity to Lena Luthor before her brother Lex did. This didn't go according to Mxyzptlk's plan; each scenario begot bigger and bigger ramifications. Soon, Kara wished she never even met Lena, which resulted in Lena becoming a tyrannical villain who took over National City. In the end, Kara resolved to leave the timeline the way it was, but walked away with a new sense of clarity about her relationship with Lena. Though it wasn't the fix he proposed, it was a resolution nonetheless, and she released him from his bond.
"We knew that we wanted to redeem Mxyzptlk from the previous incarnation, and we felt that we wanted him to come and apologize for his bad behavior to Kara and make amends. So that was part of recasting and having him appear in a more benign and contrite and charming form," showrunner Jessica Queller explained to CBR. "Not that the previous actor wasn't charming, but the character was a little bit malevolent. Then we just got so blessed with the casting of Tom Lennon, who is magic himself."
Airing Sundays at 9 p.m. ET/PT on The CW, Supergirl stars Melissa Benoist as Kara Danvers, David Harewood as Martian Manhunter and Chyler Leigh as Alex Danvers.