5. Barbara "Bunny" Fletcher
Barbara "Bunny" Fletcher (Markie Post) was the mother of Erin Lindsay (Sophia Bush), and calling her a bad mother would be a bit of an understatement. The character did not look after Lindsay and her brother when they were kids, and a lot of Lindsay's hang-ups as an adult stem her fraught dynamic with her.
Fletcher is constantly undermining Lindsay and the other IU cops throughout the show, culminating in her decision to MURDER her boyfriend in season 4. Voight has Fletcher dead to rights, but decides to cover it up as a favor to Lindsay.
There were some moments that elicited sympathy for the character, but overall, Fletcher was a tough pill to swallow.