Jacksepticeye

McLoughlin was raised in County Offaly, Ireland, as the youngest of five siblings. He developed an interest in video games around age seven and took up playing the drums during his youth, eventually becoming a fan of heavy metal music after being introduced to the genre by his older brother. During his late teens and early twenties, he played drums for the melodic death metal band Raised to the Ground, releasing the EP Risen from the Ashes with the group in 2009. He has been diagnosed with autism and attention deficit hyperactivity disorder (ADHD).

McLoughlin was in a relationship with Danish social media creator Signe Hansen from 2015 to 2018. Since 2019, he has been in a relationship with Dutch YouTuber Evelien Smolders, commonly known online as Gab Smolders. After residing in Athlone, Ireland, where he completed his university education, he relocated to Brighton, England, in 2017.

McLoughlin launched his YouTube channel in 2007 but began uploading regular content in late 2012, initially focusing on voice impressions before transitioning to video game commentary. In September 2013, he gained significant attention after winning a shout-out competition hosted by PewDiePie, causing his subscriber base to grow from 2,500 to 15,000 in four days. By May 2014, the rapid expansion of his channel allowed him to pursue online video production as a full-time profession, reaching one million subscribers later that year.

His content largely consists of Let's Play playthroughs spanning indie titles, horror releases, and major mainstream games, alongside comedic sketches and vlogs. His videos became widely recognized for their fast-paced editing, improvised commentary, and distinct branding, including his green eye logo, Septic Eye Sam, and his introductory greeting, "Top of the morning to ya, laddies." He has frequently collaborated with other prominent creators, including Markiplier and PewDiePie, and has used his platform to advocate for mental health awareness and promote his community slogan, "positive mental attitude."

In 2017, McLoughlin began expanding into live performances and television, appearing on Disney XD's programming block Polaris: Player Select and embarking on his solo stage tour, How Did We Get Here?, alongside touring dates with Game Grumps. In 2022, he released a biographical documentary under the same title, documenting his journey from rural Ireland to digital stardom.

McLoughlin has also taken on voice acting and film roles. He made a cameo appearance as himself in the 2021 feature film Free Guy starring Ryan Reynolds, for which he also advised director Shawn Levy on authentic video game culture. His voice-acting credits include roles in games such as Bendy and the Ink Machine, Monster Prom, River City Girls, Poppy Playtime, and Dispatch, as well as an appearance in the animated series Sonic Prime.

Throughout his career, McLoughlin has been recognized for organizing charity initiatives. Beginning in 2018, he established "Thankmas", an annual December charity livestream campaign that mobilizes creators and viewers across multiple platforms. Through Thankmas and other fundraising streams, he has generated tens of millions of dollars for causes including World Central Kitchen, Crisis Text Line, Save the Children, and New Story. In 2022, his charitable efforts were recognized with the Best Philanthropic Streamer honour at The Streamer Awards.

Beyond online video, McLoughlin founded Top of The Mornin' Coffee in June 2020, partnering with the hunger-relief organization Feya Foundation. In 2018, he co-founded the gaming-focused apparel brand Cloak alongside Markiplier, eventually stepping down from the company in 2023. In 2023, he launched the podcast Brain Leak with creator Ethan Nestor and debuted the comic book series Altrverse with publisher Bad Egg.