Scottish-born inventor and scientist who is credited with patenting the first practical telephone in 1876, beating Elisha Gray to the patent office by hours. His work grew from research into hearing aids for the deaf (his mother and wife were both deaf). Bell also invented the photophone, an early metal detector, and worked on aeronautics. The telephone transformed global communication; Bell's patent was the most valuable in US history at the time.

• Nationality: scottish-canadian
• Roles: inventor, scientist, engineer