MOUNTAIN VIEW, Calif. — The gallery of photos lining a hallway at Google’s headquarters here is filled with the faces of luminaries who have visited the company: Mikhail Gorbachev, Bill Clinton, the Dalai Lama, Muhammad Ali and Jane Fonda.

And in each of the more than 100 pictures, there is someone else: Tan Chade-Meng, a geeky fellow with a big smile who is a household name only in his own household.

Mr. Tan is a 37-year-old engineer at Google, and his initial chutzpah, his quirky workplace and a steady stream of distinguished visitors have turned him into the company’s in-house Zelig.

The visitors are often there to get a glimpse of the future in progress, and perhaps something to drop into conversation that suggests an advanced I.Q.: “When I was out at Google the other day...”