레논, 스테브

Lennon played county darts for Kilkenny and Kildare. Lennon has played professional darts since 2011. He first won a tournament in the Ireland Players Championship, beating Stephen Byrne 6–1 in the Final. In 2016, he made it to the Final of Finnish Masters, beating Dennis Nilsson.

Lennon entered the Professional Darts Corporation's Qualifying School in 2017, and picked up a Tour Card on the third day.

He made his World Championship debut in 2018 but lost 2–3 to Michael Smith in the first round.

Lennon made it to the final of the 2018 Dutch Darts Masters, where he lost out to Michael van Gerwen. He reached the quarter-final of the 2018 Players Championship Finals, again losing to van Gerwen.

Following Gary Anderson's withdrawal from the 2019 Premier League, Lennon was selected as one of nine 'contenders' to replace him. He played Peter Wright on Night 3, in Dublin. Lennon took a 3–0 lead, only to lose 7–5.

In June 2019, Lennon alongside William O'Connor made it all the way to the final of the 2019 PDC World Cup of Darts where they eventually lost to Scotland 3–1.

He enjoyed one of his finest days in the PDC on 22 February 2020 when he got to the semi-finals of Players Championship 5, only to lose narrowly to Gerwyn Price. Lennon had three averages of over 100. He hit his first PDC nine-dart finish in his last 32 game against Kai Fan Leung.

Unable to qualify for any ranking major apart from UK Open in 2022, Lennon dropped down in ranking. He missed his first World Championship in six years, but managed to stay within top 64 of PDC Order of Merit and continued on the Pro Tour in 2023.

In 2023 Lennon continued to struggle, missing out on PDC World Cup of Darts for the first time since 2017. He qualified for 2023 Grand Slam of Darts, but did not qualify from the round robin. He was also able to qualify for 2023 Players Championship Finals and was eliminated in Second Round. After one year absence he returned to Alexandra Palace for 2024 PDC World Darts Championship. Lennon came back from 0–2 on sets against Owen Bates in the First Round and won 3–2, giving him chance to keep his Tour card. However, he lost in Second round against Jonny Clayton 1–3 and finished the season on 66th place in PDC Order of Merit.

Lennon lost his Tour card after 2023 season, but managed to win his Tour card back on first day of UK Q-School 2024, defeating William Borland 6–4 and securing his position for seasons 2024 and 2025. In the 2024 PDC Players Championship series, Lennon made the quarter-finals of event 3, defeating Adam Warner 6–5, Gerwyn Price 6–3, Dimitri Van den Bergh 6–3 and Ritchie Edhouse 6–4 before losing to Michael van Gerwen 6–5.