William Bosi

William (Will) Bosi (born 27 December 1998) is a Scottish professional rock climber specializing in sport climbing, bouldering and competition climbing.

Bosi is only the second British sport climber in history to redpoint a graded sport climbing route (King Capella in 2021), and by 2023, was one of only a small group of climbers in the world to have completed a boulder (Alphane in 2022, Burden of Dreams in 2023, and Return of the Sleepwalker in 2024).

Bosi was born in Edinburgh to Alison and Martin Bosi.

His mother is a nursery nurse from Inverleith.

Both parents took him and his 3-year-old brother Alexander to an indoor climbing centre in Newhaven, Edinburgh when he was 6 years old.

He attended Broughton High School, Edinburgh.

By 2011, Bosi was the British Champion in the Youth Climbing Series (a competition climbing event for boys aged 11 to 13) and also the Scottish Youth Climbing Champion.

In 2016, Bosi came to attention when aged 17 he redpointed Steve McClure's famous British sport climbing route Rainshadow, becoming the youngest Briton to climb a graded sport route.

Bosi has represented Britain in competition lead climbing, in both youth and adult formats, and in 2018 became the first Briton to reach an International Federation of Sport Climbing (IFSC) final in 30 years, where he finished fifth at the IFSC World Cup in Chamonix; he finished fourth twice during the 2019 IFSC World Cup.

In 2020–2021, Bosi became only the second British climber in history, after Steve McClure, to climb a grade sport route with his repeat of Adam Ondra's La Capella, and followed up by his first free ascent of King Capella (a route initially considered a possible 9b+), both of which are in Siurana in Spain.

In 2022, on a trip with Adam Ondra to his home crag of Moravský Kras in the Czech Republic, Bosi flashed the boulder, Charizard (he failed on Ondra's as yet unrepeated 8C+ boulder, Terranova).

That year, he also created Honey Badger in the English peak district, which he graded at.

In November 2022, Bosi became one of only a handful of boulderers in the world to have climbed a grade boulder when he repeated Shawn Raboutou's Alphane, which he felt was easier than his own 8C+ graded route, Honey Badger.

In April 2023, he made the first repeat of Nalle Hukkataival's Burden of Dreams, considered the world's first-ever boulder, and which at the time of Bosi's repeat was still considered the world's hardest boulder.

In February 2024, Bosi made the first repeat of Daniel Woods' Return of the Sleepwalker, which he felt was easier than Burden of Dreams, but harder than Alphane, with Bosi stating that Woods' route was definitely at a V17 grade.

Bosi narrowly missed out on a place in the Tokyo 2020 Olympics, despite trying to learn speed climbing, a required discipline in Olympic competition climbing.

In 2021, Bosi announced that he was taking a break from competition climbing to focus on outdoor sport climbing and bouldering.