MallowbyNames

Gillermo

gih-YAIR-moh · Of uncertain origin; possibly a variant of Guillermo, the Spanish form of William, meaning 'resolute protector'.

Peak popularity
1929
Usually for
Boys
Trend
Holding steady

Holding steady.

Popularity of Gillermo since 1922

Babies named Gillermo per year in U.S. Social Security records. Raw births topped out in 1993, but relative to how few babies were recorded back then, Gillermo's real moment was 1929.

7142119602000Most births 1993Boys
Data table (by decade)
DecadeBoys
1920s55
1930s33
1940s39
1950s56
1960s38
1970s112
1980s103
1990s138
2000s54
2010s5
2020s0

Meaning & origin

Gillermo is an exceedingly rare variant of Guillermo, the Spanish form of William. First recorded in 1922, the name saw its peak usage in 1929, but has since remained extremely uncommon, with no rank in recent decades. Its trajectory is stable, indicating consistent but minimal use over time. This name has no strong association with particular states or cultures beyond its Spanish roots, making it a distinctive choice for families seeking a unique twist on a classic.

Gillermo appears to be a rare variant or misspelling of Guillermo, which is the Spanish form of Germanic William, derived from 'wil' (will, desire) and 'helm' (helmet, protection). Despite its early recording in 1922, the name has never achieved notable rank, with a peak in 1929 suggesting occasional but sporadic use.

Nicknames & variants

Nicknames: Gilly, Memo

Variants: Guillermo

Sibling names for Gillermo

Names that share Gillermo's style, for a brother or sister.

A parent animal hugging its little one, the personalized name page

G is for Gillermo, our favorite little boy.

G is for Gillermo…”

In a Mallowby alphabet book, Gillermo's letter becomes Gillermo's page: hand-illustrated, printed hardcover or paperback, made just for them.

Make Gillermo's book

Books for siblings or grandkids? The second book is 15% off.

Questions parents ask

What does the name Gillermo mean?
Gillermo is likely a variant of Guillermo, the Spanish form of William, meaning 'resolute protector', though its exact derivation is uncertain.
Is Gillermo a popular name currently?
No. Gillermo has never ranked in the top 1000 U.S. births, and its most recent data (2025) shows no rank, indicating very low usage.
Is Gillermo a boy's name?
Yes, Gillermo is typically given to boys, aligning with its masculine Spanish origin.