Who invented the Pontiac trans am?

The man most credited with it is Pontiac engineer Herb Adams. He had been head of development team on the PFST (Pontiac Firebird Sprint Turismo) in 1967-68. The special suspension parts developed for the PFST were used on the first Trans Am in 1969. Adams was head of special projects for Pontiac until the mid 1970's and raced Firebirds (and later his own renditions the "Fire-Am" and "Silverbird") in SCCA competition for several years.