image = AlexSmile.png
| full name = Alexander Ruben Constancio | nickname = AC | birth date = July 11, 1995 (18) | resides = Miami,Flordia | family = Andrew Constancio, Adam Constancio | relationships = Sarha Wright | affiliations =Austin Mahone }} Alex Constancio is 18 years old and Austin's best friend. His full name is Alexander Ruben Constancio. He was in Rebecca Black's Person Of Interest video. Alex doesn't sing much but he likes lip-syncing songs on YouTube. Alex sings in Roll With It, Street Lights and Too Much Time. Alex does weekly YouNows with[[Robert Villanueva|
- Alex was 13 when he had his first kiss.
- Alex has two brothers, Andrew and Adam.
- His favorite color is red.
- Alex is 5 feet and 6 inches
- Favorite candy is sour patch kids
- Alex was born at 7:18 a.m.
- His favorite ice cream is vanilla
- Alex likes scary movies
- He just moved in with Austin in the same day of their ShootUsDown anniversary
- He has a YouTube account
- Alex's 3 bestfriends are Austin, Robert, and Zach.
- Alex admits that he loves peanut butter with sugar
- He is skater
- Wants to be an actor
- His favorite song of Austin's is "Shawty Shawty"
- Alex believes in luck
- He is 18 years old.
- He is Taken.
- He lives in Miami,Flordia
- He loves the number 711 because it is his brithday
- He's from Italy
- He likes Basketball and Football