Alistair MacDerrick

Alistair of House MacDerrick, laird of Phlarticap and Harx, governor of the Earth and Moon, etc., is a Reticulan, specifically the highest-ranking official on Earth. He is very likely to be Wilt's father.

In Slow Food, Gnrth mentions having "gone through" several of Alistair's children, implying he has fathered many. Glo confirms this in Terms & Conditions by specifying Alistair's harem is "twice as large as all the others combined".