Definition of "overlord"

The leader is the man who knows the way of the overlords but identifies with the life of the oppressed.

1981, William Irwin Thompson, The Time Falling Bodies Take to Light: Mythology, Sexuality and the Origins of Culture, London: Rider/Hutchinson & Co., page 195

Warlords leveraged their veteran soldiers to seize living space while the Council races were still grateful. Over centuries, the krogan conquered world after world. There was always "just one more" needed. When the Council finally demanded withdrawal from the asari colony of Lusia, krogan Overlord Kredak stormed off the Citadel, daring the Council to take their worlds back.

2008, BioWare, Mass Effect, Redwood City: Electronic Arts, PC, scene: Krogan: Krogan Rebellions Codex entry

One thing is for certain, there is no stopping them; the ants will soon be here. And I, for one, welcome our new insect overlords.

1994 February 24, David Mirkin, “Deep Space Homer”, in The Simpsons‎, season 5, episode 15, spoken by Kent Brockman

Fluffy is wearing a diamond collar that belongs in the Tower of London with a platoon of Beefeaters standing guard over it. "I for one welcome our new feline overlords."

2009, Charles Stross, The Jennifer Morgue‎, page 239

“It’s not like young authors need to worry about being supplanted now,” Ms. Williams said. “It’s a worry. But it’s got a ways to go, at least. They haven’t become our overlords yet.”

2023 February 23, Michael Levenson, quoting Sheila Williams, “Science Fiction Magazines Battle a Flood of Chatbot-Generated Stories”, in The New York Times‎

Poor Johnny one-note sang out with gusto / And just overlorded the place

1937, Rodgers and Hart (lyrics and music), “Johnny One Note”