Francisco García Diego y Moreno (17 September 1785 – 30 April 1846) was a Spanish Catholic prelate who served as the first Bishop of the Californias.

In 1801, he received the habit of Francis at the missionary College of Guadalupe de Zacatecas, made his vows the following year and was ordained a priest at Monterrey, Nuevo León, 14 Nov 1808.

On 19 Sep 1836, the Mexican government decided to petition the pope to create California a bishopric and congress at the same time decreed to pay the new bishop an annual salary of $6,000 until the diocese should have a sufficient income.

Of the three candidates proposed by the metropolitan chapter on 22 June 1839, the Mexican government on 6 April 1840, recommended Father Francisco Garcia Diego.

When he arrived, there were only seventeen Franciscan Fathers, mostly aged and infirm, in charge of the twenty-one secularized Indian missions and six Spanish towns.

Worn out by hardships and disheartened at the deplorable conditions which he could not remedy, Bishop Diego died, and was buried in the old Mission Santa Barbara.