NEW YORK — On ‘‘Shameless,’’ William H. Macy plays the world’s most deadbeat dad.

He stars as Frank Gallagher, a boozy, shiftless grifter whose brood of six mix-and-match offspring (do any of them share the same mother?) care for one another and, by necessity, him. The oldest daughter, Fiona (played by Emmy Rossum), is the family’s de facto mom, a Wendy to Frank’s derelict Peter Pan.