[Maxxie.]

Very detailed so your welcome:

Show 1:
- Connie Talbot (BGT runner-up 2007)
- Diversity (BGT winner 2009)
- Jack Carroll (BGT runner-up 2013)
- Jonathan Goodwin (BGT finalist 2019)
- Signature (BGT runner-up 2008)
+
- Piff the Magic Dragon (comedy magician, America's GT 2015 finalist)
- The Sacred Riana (horror magician, Asia's GT winner 2017)
- Salah (dancer, Winner of France '06, Italy '17 and the Middle East '15)
- Sara and Hero (dog act, America's GT, 2017 finalists)
- Zara Larsson (singer, Sweden's GT winner 2008)

Show 2:
- Aquabatique (BGT finalist 2012)
- Boogie Storm (BGT finalist 2016)
- Lost Voice Guy (BGT winner 2018)
- Paddy & Nico (BGT finalist 2014)
- Richard Jones (BGT winner 2016)
+
- Choi Sung-bong (opera singer, South Korea runner-up, 2011)
- Drew Lynch (comedian, America's GT runner-up, 2015)
- Kechi Okwuchi (singer, America's GT 2017 finalist)
- Terry Fator (singer/ventriloquist, America's GT 2007 winner)
- Timomatic (singer/dancer, Australia's GT, 2011 finalist)

Show 3:
- George Sampson (BGT winner 2008)
- Hollie Steel (BGT finalist 2009)
- Kojo Anim (BGT finalist 2019)
- Ronan Parke (BGT runner-up 2011)
- Susan Boyle (BGT runner-up 2009)
+
- Colin Cloud (mentalist, America's GT semi-finalist 2017)
- Eric Chien (magician, Asia's GT winner 2019)
- Kodi Lee (singer, America's GT currently competing)
- Prince Dance Group (dance troupe, India's GT winner 2006)
- Tape Face (mime act, America's GT finalist 2016)

Show 4:
- Calum Scott (BGT finalist 2015)
- Darcy Oake (BGT finalist 2014)
- Flawless (BGT finalists 2019)
- Robert White (BGT runner-up 2018)
- Shaheen Jarfagholi (BGT finalist 2009)
+
- Angelina Jordan (singer, Norway's GT winner 2014)
- Kseniya Simonova (sand artist, Ukraine's GT winner 2009)
- Paul Zerdin (ventriloquist, America's GT winner 2015)
- Tyler Butler-Figueroa (violinst, America's GT currently competing)
- Viktor Kee (juggler, America's GT finalist 2016)

Show 5:
- Attraction (BGT winners 2013)
- Daliso Chaponda (BGT finalist 2017)
- Francine Lewis (BGT finalist 2013)
- Giang Brothers (BGT finalists 2018)
- Issy Simpson (BGT runner-up 2017)
+
- Courtney Hadwin (singer, America's GT finalist 2018)
- Johnny Manuel (singer, America's GT semi-finalist 2017)
- Leo Rojas (panpipe player, Germany's GT winner 2011)
- Lindsay Stirling (violinst, America's GT quarter-finalist, 2010)
- Liu Wei (armless pianist, China's GT winner 2010)

Show 6:
- Bars and Melody (BGT finalists 2014)
- Ben Hart (BGT finalist 2019)
- Paul Potts (BGT winner 2007)
- Stavros Flatley (BGT finalist 2009)
- Tokio Myers (BGT winner 2017)
+
- Cosentino (escape artist, Australia's GT runner-up 2011)
- Kenichi Ebina (dancer, America's GT winner 2013)
- RDC (dance troupe, Ireland's GT winners 2018)
- Shin Lim (magician, America's GT winner 2018 + champions)
- Sons of Serendip (classical quartet, America's GT 2014 finalists)

Show 7:
- Ashleigh & Sully (BGT winner 2012 [with Pudsey])
- Colin Thackery (BGT winner 2019)
- Collabro (BGT winners 2014)
- Marc Spellman / X (BGT runner-up 2019)
- Twist & Pulse (BGT runners-up 2010)
+
- Brian Justin Crum (singer, America's GT finalist 2016)
- Cristina Ramos (opera/rock singer, Spain's GT winner 2016)
- Darci Lynne Farmer (ventriloquist/singer, America's GT winner 2017)
- DJ Arch Jnr (3 [now 7] year old DJ, South Africa's GT winner 2015)
- Preacher Lawson (comedian, America's GT finalist 2017)

2 from each show go through plus wildcards making 16 in the final