Trinity High School (also known as Euless Trinity in sports) is a public high school in Euless, Texas. The school serves grade levels 10–12 and is a part of the Hurst-Euless-Bedford Independent School District.

The school is named "Trinity" as an homage to the three cities comprised by the school district in which it is located: Hurst, Euless, and Bedford (and also as a reference to the nearby Trinity River, which forms the southern border of the school district). The school's mascot is a Trojan. The Trinity High School football team has won the Texas 5A Division 1 State Championship three times (2005, 2007, 2009).

As of 2025, education platform Niche ranked Trinity High School as the most diverse public high school in Texas and the 16th most diverse public high school in the country based on student demographics and parent/student surveys. In 2017, the school was rated "Met Standard" by the Texas Education Agency, with a 5-Star Distinction for Academic Achievements in ELA/Reading, Mathematics, Science, Social Studies, and Post Secondary Readiness.

Trinity was established as the second high school in the Hurst-Euless-Bedford Independent School District. The first HEB ISD high school was L.D. Bell High School, which opened in 1957 in Euless, but moved to its current site in Hurst in 1965. The Trinity campus sits on a hillside in west central Euless, less than 500 feet from the Euless-Bedford city limit.

In November 2023, voters approved an HEB ISD bond package that included plans to replace Trinity High School's current buildings with a new building at the same campus.

Trinity High School is made up of eleven distinct buildings, most of which are named for the department they house (often abbreviated to just the first letter). The nine original buildings were: the Fine Arts Building, the Academics Building, the Library, the Science Building, the Physical Education Building, the Cafeteria, the Driver's Education Building, a small two-story building called D-Building, and an Administration Building. The Physical Education building formerly included a natatorium that was mothballed and eventually demolished in the 2010s. The late 1990s brought three major changes to the campus: a system of covered walkways was built to connect most of the school's buildings, a new band hall was added to the Fine Arts Building, and a wing was added to the Academics Building. This new wing became the new face of the campus because of its large and prominent façade and provided new offices for the principal, assistant principals, and secretaries. The original Administration Building was converted to house the counselors' offices.

In the first few years of the new millennium, two new buildings were added to the Trinity campus. The two-story N-Building lies on the campus's southern edge and houses the Foreign Language Department and many classes of and the office of the coordinator of the International Baccalaureate program. Just a little further into campus from the D-Building is the new W-Building. The W-Building houses special education classrooms and is specifically designed to accommodate the needs of students with physical disabilities. An activity center named for former principal B.J. Murray opened in 2013 with a 70-yard indoor field, offices, locker rooms, and a weight room dedicated after Trinity alum Ryan McBean. The center is colloquially referred to as "the Mac".

During the 2016–2017 school year, Trinity High School enrolled 2,574 students in grade 10 (34.4%), grade 11 (34.0%), and grade 12 (31.6%). Ethnicities represented include white (31.3%), Hispanic (29.2%), African Americans (21.4%), Asian and Pacific Islander (9.9%), Native Hawaiians and Pacific Islander (3.2%), two or more races (4.3%), and Native American (0.8%). Forty-eight percent were economically disadvantaged.