c. 1793, William Blake's derisive name for the anthropomorphic God of Christianity. The name reflects nobody + daddy.
Entries linking to nobodaddy
nobody n.
c. 1300, no bodi "no person no one," from Middle English no (adj.) "not any" + bodi (see body (n.)). Written as two words 14c.-18c.; hyphenated 17c.-18c. Incorrect use with their is attested from 1540s. Meaning "person of no importance, one who is not fashionable in society" is from 1580s.
daddy n.
c. 1500, colloquial diminutive of dad, with -y (3). Slang daddy-o is attested by 1949, from bop talk.
Daddy-long-legs is from 1814 in Britain as "crane-fly," a slender, long-legged summer fly. In the U.S., it was used by 1865 as the word for a spider-like arachnid with a small round body and very long, slender legs.
A superstition obtains among our cow-boys that if a cow be lost, its whereabouts may be learned by inquiring of the Daddy-Long-legs (Phalangium), which points out the direction of the lost animal with one of its fore legs. [Frank Cowan, "Curious Facts in the History of Insects, Including Spiders and Scorpions," Philadelphia, 1865]