Mister Dubowski is a recurring background character.
He has an orange moustache and wears glasses.
In the dodgeball gym he and the tall black-haired woman are standing on either side of Henry behind Coop and Dennis. She is not Dennis' Mom.
Shown sitting with an orange-haired boy also with glasses who might be Dubowski's son, along with the waitress who is the mother of the Turtle girl.
This is the episode where Dennis reveals his name while narrating his and Coop's greeting to him
Shown shopping with a taller black-haired woman.