Sherman was the possible father of Gloria and the husband of Dorothy.
History
He is mentioned in the season 4 episode "Walnuts and Demerol" when Dorothy and Evelyn tell to Gloria and Charlie that they cannot sleep together because they can be Half-Siblings. When Gloria were still not born, he had an affair with Evelyn and Evelyn's husband with Dorothy. Hence, it is unknown who is Gloria's biological father. It can be or Frank Harper or Sherman because both had sex with Dorothy.