In the films, he’s not. But in the books, his race is never explicitly stated. We know that he has his father’s messy black hair, and we know that is mother is a pale redhead and he has her green eyes. It’s entirely plausible that James could have been black (or another race that isn’t white) and therefore Harry would be mixed race. A lot of people - including me - really love this idea.
here are some really good posts about it:
and this quote from this article:
Vondell has most recently channeled his search for representation and identity into illustrations of Harry Potter, from the unique lens of Harry Potter as a black, mixed-race kid. “I’ve been rereading Harry Potter and I realized that his race in the books was never defined. It was never defined except to say that he has startling green eyes and jet-black uncontrollable hair. And to me, what I read into that was that he’s a mixed kid.”
The illustrations proved popular, striking a chord both inside and outside his social media audience, prompting a host of responses. “It took off because so many people were like, ‘Oh my God, Harry Potter could easily be a black, mixed-race hero story.’ I’ve heard from so many people like, ‘I’ve been wanting this.’ It’s really interesting to hear from people of color, particularly black, mixed-race people like me saying, ‘I’ve never had this.’ That’s something that really struck me, because I realized I didn’t have that either. There are so few hero stories with centralized black characters.”
and my fave mixed race harry fanart: