As someone with Mental Illness,  I absolutely love that portrays it. Films, Series and Animation (in particular), this is a list of charecters from different Shows and Films that have charecters with different Mental Illness'.
Note: Most of these are never diagnosed, but seem very obvious if you look into the charecters ( in no order) :

•Bojack Horseman (BPD and MDD) from Bojack Horseman (2014 - 2020)
•Winnie the Pooh (ED) from Winnie the Pooh (Many Shows, Books and Movies) 
•Eric Cartman (APD) from South Park (1997 - )
•Rick Sanchez (BPD and MDD) from Rick and Morty (2013 - )
•Stewie Griffin (ODD) from Family Guy (1999 - )
•Piglet (GAD) from Winnie the Pooh (Many Shows, Books and Movies) 
•Filburt Turtle (GAD and Hypochondria) from Rockos Modern Life (1993 - 1996) 
•The Joker (APD) specifically from The Dark Knight (2008)
•Brian Griffin (NPD and MDD) from Family Guy (1999 - )
•Travis Bickle (SPD) from Taxi Driver (1976)
•Tiger (ADHD) from Winnie the Pooh (Many Shows, Books and Movies) 
•Eeyore (Dysthymia) from Winnie the Pooh (Many Shows, Books and Movies) 
•Peter Griffin (APD and Mental Disability) from Family Guy (1999 - )
•Dennis Reynolds (NPD) from It's Always Sunny in Philadelphia (2005 - )
•Lee Chandler (MDD and PTSD) from Manchester by the Sea (2016)
•Santa's Little Helper (PTSD) from The Simpsons (1989 - )
•Rabbit (OCD) from Winnie the Pooh (Many Shows, Books and Movies) 
•Ronald "Mac" McDonald (BPD) from It's Always Sunny in Philadelphia