Boy Names That End in O

Ranked in the United States in 2025, with birth trends and peak years.

O is the 4th most common last letter for baby boys' names in the United States, with 20 names ending in O in the top 300 for 2025, led by Mateo (#8). Of those, Thiago is the fastest-growing, now 2.6 times as common as in 2020.