Thomas Matthew DeLonge (/dəˈlɒŋ/; born December 13, 1975) is an American musician and songwriter best known as the co-founder, co-lead vocalist, and guitarist of the rock band Blink-182 across three stints (1992–2005, 2009–2015, and since 2022). He is also the lead vocalist and guitarist of the rock band Angels & Airwaves, which he formed in 2005 after his first departure from Blink-182. DeLonge is noted for his distinctive nasal singing voice.

DeLonge received his first guitar as a child and later began writing punk rock songs. While in high school, he formed Blink-182 with bassist Mark Hoppus and drummer Scott Raynor. They signed with Cargo Music and released their debut album, Cheshire Cat (1995), which made them popular in the local scene. Their second album, Dude Ranch (1997), was released by MCA Records and featured the hit single "Dammit". Travis Barker replaced Raynor in 1998 and the group achieved widespread success with their third album, Enema of the State (1999), which featured three hit singles; it sold more than 15 million copies worldwide and went quadruple-platinum in the U.S. The band's fourth release, Take Off Your Pants and Jacket (2001), gave them their first No. 1 album.

DeLonge and Barker experimented with post-hardcore music on the album Box Car Racer (2002), which they released under the name Box Car Racer, but the side project was dissolved the next year. Blink-182's untitled fifth album, also known eponymously as Blink-182 (2003), reflected a change in tone. Following internal tension spearheaded by DeLonge, the band broke up in 2005 before reuniting in 2009. During their initial breakup, DeLonge formed Angels & Airwaves, which has released five albums and evolved into what he calls an "art project" encompassing various forms of media. In 2015, DeLonge once again departed from Blink-182 before returning a second time in 2022.

Outside of music, DeLonge has founded companies such as Macbeth Footwear, which sells vegan and organic clothing; Modlife, which sells technology designed to help artists monetize their creations; and To The Stars, which is dedicated to the exploration of fringe science. He scored and produced the sci-fi film Love (2011), has multiple film projects in development, and wrote the children's book The Lonely Astronaut on Christmas Eve (2013).

Thomas Matthew DeLonge was born in Poway, California, on December 13, 1975, the son of mortgage broker, Constance (née Lovell), and oil company executive Thomas Lyon DeLonge. He has a brother, Shon, and a sister, Kari. He is of German and Mexican descent. His first musical instrument was a trumpet, which he received as a Christmas gift at age 11. He originally planned to become a firefighter, and participated in the San Diego Cadet Program. He first picked up the guitar from a friend at church camp, and became preoccupied by the instrument. Two friends in the sixth grade gave him his first guitar as a Christmas present, which he called a "beat-up, shitty acoustic guitar that was worth about $30".

In seventh grade, DeLonge visited a friend in Oregon who introduced him to the music of Stiff Little Fingers, the Descendents, and Dinosaur Jr. He consequently dyed his hair purple and began practicing the guitar in his bedroom. His first concert was the band Chemical People. He attempted to form a band named Big Oily Men, which was essentially a one-man band because its lineup consisted of whomever he could persuade to join him for short periods. He first began skateboarding in the third grade, and it consumed much of his time outside of school: "I lived, ate, and breathed skateboarding. All I did all day long was skateboard. It was all I cared about." He and friends would begin at one side of San Diego and attempt to skateboard to the other, pranking people in the process. DeLonge was an average student, later saying: "I knew exactly how hard I had to work in school. As long as I got that C, I wouldn't try one minute extra to get a B. I just cared about skateboarding and music."

DeLonge's parents fought constantly during his formative years, culminating in a divorce when he was 18. Shortly thereafter, his mother lost her job. He promptly moved out, feeling that he needed to start his own life; his brother was also away at that time in the Army, and his departure affected his family: "My mom and sister were left asking, 'What happened to our family?'" After high school, he worked on construction sites, driving a diesel truck and handling concrete and piping: "I hated, hated, hated my job. You know those people who hate their job? That was me." He quit when Blink-182 signed with MCA Records in 1996.

DeLonge formed his first successful band, Blink-182, in 1992. He was removed from Poway High School in the second half of his junior year for going to a basketball game while inebriated. He was forced to attend a different school for one semester, nearby Rancho Bernardo High School, where he became friends with Kerry Key, and his girlfriend, Anne Hoppus. Rancho Bernardo organized Battle of the Bands competitions, and DeLonge signed up, performing an original song titled "Who's Gonna Shave Your Back Tonight?" to a packed auditorium. Drummer Scott Raynor was at the competition with his own group, which soon dissolved, after which he was introduced by friend Paul Scott to DeLonge at a party. The two began to organize jam sessions at Raynor's home, shifting through various bassists. The following summer, his desire to be in a legitimate band increased significantly – Anne Hoppus characterized Delonge's passion as "incessant whining and complaining". Her brother, bassist, Mark Hoppus, was new to San Diego and she introduced the two one night that August. The two would jam for hours in DeLonge's garage, exchanging lyrics and writing new songs.^{[citation needed]}