Giovanni Tacci Porcelli known as Giovanni Tacci[a] (12 November 1863 – 30 June 1928) was an Italian prelate of the Catholic Church who was Bishop of Città della Pieve for twenty years, then a papal ambassador, and finally secretary of the Congregation for the Oriental Churches from 1922 to 1927.

He then did pastoral work in Fermo and Rome until 1895 and was raised to the rank of domestic chamberlain of his holiness.

On 18 March 1895, he was appointed Bishop of Città della Pieve by Pope Leo XIII.

[5] Pope Benedict XV made him Cardinal-Priest of Santa Maria in Trastevere in the consistory of 13 June 1921.

On 17 September he was made a member of the Congregation for the Doctrine of the Faith and on 24 November of the Pontifical Commission for the Interpretation of the Code of Canon Law.