This is Henry Citron! He's known Ford since Ford first came to Gravity Falls. Ford spent hours each day in the library, and they became firm friends. 30 years on, and they're closer than ever (but don't tell Stan he'll get jealous)

He has a heightened sixth sense, meaning Ford finds him very useful when it comes to investigating the mysteries of Gravity Falls. However, he's also extremely susceptible to mind control, and the few detached bits of Bill's essence can control him...