Who Founded Y Combinator? Paul Graham and the Real Story

• Paul Graham (PG): essayist, programmer, cofounder of Viaweb (sold to Yahoo for $49M in 1998). Designed the YC model. Ran the program from 2005 to 2014.

• Jessica Livingston: ran marketing at a Boston investment bank before YC. Author of 'Founders at Work.' Her people-reading ability is widely credited as the actual filter behind YC's selection. Married Paul Graham in 2008.

• Robert Morris: MIT professor, creator of the 1988 Morris worm (the first major internet worm), cofounder of Viaweb with PG.

• Trevor Blackwell: engineer, founder of Anybots (humanoid robotics), the technical builder of YC's early infrastructure.

In March 2005, Paul Graham gave a talk at Harvard called 'How to Start a Startup.' Several students asked for funding afterward. Rather than pick one, PG, Jessica, Robert, and Trevor decided to fund a batch — eight teams over a summer in Cambridge, Massachusetts.

They called it the 'Summer Founders Program' and intended it as a one-time experiment. The first batch (S05) included Reddit, Justin.tv (later Twitch), Loopt, and Wufoo. The experiment worked. They ran another batch in Winter 2006 — and Y Combinator was a permanent institution.

The name comes from a concept in lambda calculus — a function that allows recursion in languages without native recursion. Paul Graham, a Lisp programmer, found the metaphor irresistible: a function that helps other functions exist. YC helps startups exist.

Garry Tan has been CEO since January 2023. Michael Seibel and Dalton Caldwell are Managing Directors. Paul Graham stepped back from day-to-day in 2014 (Sam Altman took over until 2019). Jessica Livingston is no longer involved in operations but remains a key figure in the YC origin story.