Comics with a focus on mental health issues, usually one that the author has personally dealt with. There’s a mix of serious and comedic approaches, often within the same strip. (Most of these also deal with trauma of some kind, so read with caution if necessary.)
Cracks of Sunshine: gag-a-day, ongoing. Related to life with DID, PTSD, and gender issues.
Gemini: The Webcomic about Living Plural: gag-a-day, ongoing. Life with DID.
Rooster Tails: gag-a-day, autobiographical, ongoing. Lots of stuff about gender issues, mostly upbeat and friendly.
Trans Girl Diaries: gag-a-day, rarely updating. Sometimes NSFW. Also about gender issues, but snarkier and darker.
Venus Envy: comedy-turned-drama, veeery rarely updated. Sometimes NSFW. Sometimes touching, often funny adventures of a trans girl adjusting to her new school.
Look Straight Ahead: drama story, completed. Recced recently, but I would be remiss if I left it out of a reclist like this. A young man struggles through a mental break with reality.