Edward Wong Hau Pepelu Tivruski IV, AKA Radical Edward, is the most comical and eccentric of Cowboy Bebop's main characters. The androgynous young hacker is also the most enigmatic of the Bebop's crew members, and many first discovering the show may wonder what gender they're supposed to be. The anime makes it clear that Ed was assigned female at birth, and is mostly referred to by "she/her" pronouns in English, but there's enough ambiguity for not only fans but even the series' creator to be uncertain of Ed's gender identity.
Ed is first introduced in Cowboy Bebop Episode 9, "Jamming With Edward." Much of the episode involves Spike, Jet and Faye trying to track down the hacker Radical Edward and getting mixed information -- Jet's "profile" on Ed ends up being "a seven-foot ex-basketball pro Hindu guru drag queen alien." After Ed teams up with the Bebop crew to take down the MPU satellite, she officially joins the team as Faye promised she could, despite Spike's protestations about how he hates kids. It's at the end of the episode when Faye says to Ed, "Hey, you're a girl!" The scene of Faye figuring this out isn't shown onscreen, but Ed is heard laughing after the line.
Ed mostly refers to herself in the third person, but occasionally identifies as a girl. In Episode 17, "Mushroom Samba," she declares "I'm a cowgirl," and in Episode 24, "Hard Luck Woman," her departure from the Bebop crew is acknowledged with the tagline "See you cowgirl, someday, somewhere!" In Cowboy Bebop: The Movie, Ed corrects a drag queen who assumes she's a boy while trick-or-treating. This evidence would seem to point toward Ed simply being a gender non-conforming girl rather than nonbinary, but at the same time, comments from creator Shinichiro Watanabe himself offer evidence toward the latter interpretation.
In a 2017 interview with IGN, after the interviewer pointed out Ed as a potential exception to Watanabe's pattern of teaming two men with one woman, Watanabe said of Ed, "Its gender is meaningless, we don’t need it." The interviewer then asked, "Why did you decide for Ed to be non-binary and have no gender, or have their gender be ambiguous?" Watanabe didn't explicitly point to the former or the latter interpretation but instead said, "I wanted to create a character that surpasses humanity. I personally think that he might not even be human, someone from outer space." Note that gendered pronouns aren't as commonly used in Japanese, so this "he" could be a quirk of translation.
The live-action Cowboy Bebop has only introduced Ed through a series of hints and a controversial final scene, but this version also seems to be leaving it ambiguous whether Ed is a girl or nonbinary. A non-binary actor, Eden Perkins, has been cast in the role, but this doesn't necessarily mean the character is being written as nonbinary. In interviews, Perkins has referred to the character with "she/her" pronouns; nonbinary people can use any pronouns, but the language does add to further ambiguity regarding the adaptation's intentions with the already ambiguous character.
Both the animated and live-action versions of Cowboy Bebop feature more direct non-binary representation with the character of Gren. As for Radical Edward, she seems to lean at least somewhat toward feminine identifiers, but regardless of whether she is officially nonbinary or simply an androgynous girl, it's not particularly important to her character either way. To put it most succinctly, "Edward is Edward."