The possibility of unlikely victories in the various rounds of the championship, where lower ranked teams beat higher placed opposition in what is known as a "giant killing", is much anticipated by the public. Such upsets are considered an integral part of the tradition and unpredictable nature of the championship, and the attention gained by giant-killing teams can be as great as that for winners of the championship. Almost every team in the championship has a fondly remembered giant-killing act in its history. It is considered particularly newsworthy when a top championship team suffers an upset defeat. • '''Westmeath's championship run''' (1937): After winning the
All-Ireland Junior Hurling Championship the previous year, Westmeath joined the senior championship in 1937. Defeats of
Meath,
Offaly and
Laois in the earlier rounds saw them qualify for the Leinster final for the first and only time in their history. Westmeath looked as though they would create a major upset when they were leading reigning champions
Kilkenny going into the final quarter. Two late goals gave Kilkenny a fortunate 5–3 to 2–4 victory. •
Offaly 5–10 Wexford 3–11 (29 June 1969): Offaly had been described as the
David of inter-county hurling when facing reigning
All-Ireland champions
Wexford in the Leinster semi-final. At half-time they held a 5–4 to 0–5 lead, with
Paddy Molloy scoring 3–4 of his team's total by the end. •
Offaly 3–17 Kilkenny 5–10 (13 July 1980): Undoubtedly regarded as one of the most significant days in the history of Offaly hurling. Offaly were only appearing in their sixth Leinster final ever and were looking for their first success, while Kilkenny were looking for a third consecutive provincial title. After a high-scoring first-half, Kilkenny only had a 3–6 to 1–10 lead. The game reached its climax in the final ten minutes as both sides swapped the lead several times. In the end, the Leinster final roll of honour had a new name as Offaly won the game by a point. •
Wexford 2–15 Kilkenny 1–16 (13 June 2004): Kilkenny were the red-hot favourites coming into this provincial semi-final. They were on the trail of a record-breaking seventh consecutive Leinster title and a third consecutive All-Ireland title. The game was going Kilkenny's way until the last puck of the game. Wexford had tested the champions but with time nearly up 'the Cats' still had a one-point lead. A Kilkenny clearance fell straight to
Michael Jacob who made no mistake in sending the sliotar into the net. With that the referee sounded the long whistle and Kilkenny's great run was at an end. •
Galway 2–21 Kilkenny 2–11 (8 July 2012): Galway secured their first ever Leinster title with a devastating display against a Kilkenny team seeking an eighth successive title.
Joe Canning scored their first goal after three minutes and held a commanding 2–12 to 0–4 half-time lead. A shell-shocked Kilkenny rallied in the second half but only managed to come within ten points of Galway by the end. •
Laois 0–29 Offaly 0–21 (7 June 2015): This was described as the most complete performance by Laois ever. After a week of turmoil which saw their manager,
Séamus Plunkett, resign before resuming his post, Laois added to Offaly's hurling woes with an eight-point defeat. •
Westmeath 2–22 Offaly 1–11 (1 May 2016): Offaly and Westmeath had operated in different spheres since their last championship meeting in 1976 with many believing that Offaly would record an easy victory. Offaly trailed 1–9 to 0–7 at half-time, which was not indicative of Westmeath's dominance, but into a strong wind after the break, Westmeath fired five points in five minutes to pull out of sight. •
Wexford 1–20 Kilkenny 3–11 (10 June 2017): Wexford had earlier defeated Kilkenny in the quarter-final of the
National Hurling League, however, many believed that a repeat performance six weeks later would be beyond Wexford. Their manager,
Davy FitzGerald, was also banished to the stands after an incident in the league. Kilkenny had the luxury of an early goal, however, they seemed uncharacteristically nervous.
Lee Chin was inspirational for Wexford in a play-making role at midfield as Wexford blew the championship wide open with a three-point victory. •
Westmeath 2-15 Wexford 0-21 (14 May
2022): Westmeath earned a memorable result in the Leinster Senior Hurling Championship, holding Wexford to a draw at TEG Cusack Park, Mullingar. A last-gasp goal from Derek McNicholas earned the Midlanders a 2-15 to 0-21 draw after an excellent performance; the veteran substitute raising a green flag in the fifth minute of stoppage time. Niall Mitchell provided the hosts’ other goal, while Killian Doyle was their top-scorer with 0-11 (nine frees, one ’65). Westmeath finished with 14 men, after Davy Glennon was shown a second yellow card with four minutes of normal time remaining. A win would have guaranteed place in the All-Ireland for Wexford in the Leinster Championship with a game to spare as they would have finished in the top 3 in Leinster but they were denied by a Westmeath side who also impressively beat Laois by 18 points on the final day of the Championship to finish 3 points above the relegation spot. •
Westmeath 4-18 Wexford 2-22 (21 May
2023): Westmeath defeated Wexford for the first time since
1940. It was second year in a row Wexford failed to defeat Westmeath. •
Wexford 4-23 Kilkenny 5-18 (14 May
2023): Wexford needed to defeat Kilkenny to avoid relegation to the 2024
Joe McDonagh Cup. ==Roll of honour==