François Gustave Théophile Seyrig (19 February 1843 – 5 July 1923) was a German-born French engineer, best known for designing bridges.

Seyrig contributed to the Eiffel and Company project to build the Maria Pia Bridge in Porto, Portugal, which was finished in 1877.

Seyrig presented a paper on the bridge to the Société des Ingénieurs Civils in 1878.

Later he worked for the Belgian firm Société Willebroeck in Brussels, and won the competition to build the Dom Luís I Bridge (also in Porto), beating the Eiffel proposal.

He began construction in 1881 and the bridge was finished in 1886.