Interaction Design Foundation (IDF) - Online meetup groups, mentors, and literature resources
Thinkful - Frequent events, More on the techy-side
UX Eye - Major events are speaker events, infrequent meetings, about once a month. Connects UX Designers with developers in the bay
UX Wizards of the South Bay - Good community with welcoming people. Meets up roughly once a week over zoom to work on personal projects and chat
Bridgegood Portfolio Creator - Join here. Nonprofit organization that prepares Designers of Color for tech jobs and meaningful design careers. Supported by Google.org, Golden State Warriors, and Twilio.org. 9,000+ student Creatives created a free portfolio on bridgegood.com; allows students to receive donations and attend exclusive design/tech events through their platform.
DesignBuddies Discord Server - Join here. For creatives from all walks of design. Meet new design friends, socialize, discuss design topics, attend occasional lecture events, join the book club! Demographic: younger people (but very accepting for anyone)
Designers Guild Facebook Group - more serious advice, job postings, feedback. Demographic: Older, seasoned professionals
Designerslack Community Community Finder - Find design communities in your area!
ACN: UX Facebook Group - Demographic: Asian creatives currently (or wanting to) work with UX design
Asian Creative Network Facebook Groups - created by Asian Creatives, but open to everyone. People share lots of their own work (good for inspiration and for following new creatives). Demographic: primarily asian creatives, young adults to middle aged
Although many groups may cater to certain demographics, all listed groups are welcoming of everyone.