Which chess player has taken part in the most World Championship events?

I think a natural question is, who has taken part in the most World Championship matches, but sometimes the World Championship event is a tournament...

So here is a table based on a Wikipedia page https://en.wikipedia.org/wiki/List_of_World_Chess_Championships:

(Player names are given with their national affiliation)

Date	Location	Winner	Score	Runner-up	Format Match/Tournament
Predecessor events prior to 1886
1834	United Kingdom London	France Louis de La Bourdonnais	18–7	United Kingdom Alexander McDonnell	M
1843	France Paris	United Kingdom Howard Staunton	13–8	France Pierre Saint-Amant	M
1851	United Kingdom London	Kingdom of Prussia Adolf Anderssen	15–6[a]	United Kingdom Marmaduke Wyvill	T
1858	France Paris	United States Paul Morphy	8–3	Kingdom of Prussia Adolf Anderssen	M
1862	United Kingdom London	Kingdom of Prussia Adolf Anderssen	11½–1½	German Confederation Louis Paulsen	M
1866	United Kingdom London	Austrian Empire Wilhelm Steinitz	8–6	Kingdom of Prussia Adolf Anderssen	M
1883	United Kingdom London	United Kingdom Johannes Zukertort	22–4	Austria-Hungary Wilhelm Steinitz	M
Private matches
1886	United States New York City (1–5)St. Louis (6–9)New Orleans (10–15)	Austria-Hungary Wilhelm Steinitz	12½–7½	United Kingdom Johannes Zukertort	M
1889	Spanish Empire Havana	United States Wilhelm Steinitz	10½–6½	Russia Mikhail Chigorin	M
1890–1891	United States New York City	United States Wilhelm Steinitz	10½–8½	Lands of the Crown of Saint Stephen Isidor Gunsberg	M
1892	Spanish Empire Havana	United States Wilhelm Steinitz	10–10, 2½–½	Russia Mikhail Chigorin	M
1894	United States New York City (1–8)Philadelphia (9–11)Canada Montréal (12–19)	German Empire Emanuel Lasker	12–7	United States Wilhelm Steinitz	M
1896–1897	Russia Moscow	German Empire Emanuel Lasker	12½–4½	United States Wilhelm Steinitz	M
1907	United States New York City (1–6, 15)Philadelphia (7–8)Washington, D.C. (9)Baltimore (10)Chicago (11)Memphis (12–14)	German Empire Emanuel Lasker	11½–3½	United States Frank Marshall	M
1908	German Empire Düsseldorf (1–4)Munich (5–16)	German Empire Emanuel Lasker	10½–5½	German Empire Siegbert Tarrasch	M
Jan–Feb 1910‡	Austria-Hungary Vienna (1–5)German Empire Berlin (6–10)	German Empire Emanuel Lasker	5–5	Austria-Hungary Carl Schlechter	M
Nov–Dec 1910	Germany Berlin	Germany Emanuel Lasker	9½–1½	France Dawid Janowski	M
1921	Cuba Havana	Cuba José Raúl Capablanca	9–5	Weimar Republic Emanuel Lasker	M
1927	Argentina Buenos Aires	France Alexander Alekhine	18½–15½	Cuba José Raúl Capablanca	M
1929	German Empire Wiesbaden (1–8, 24–25)Heidelberg (9–11)Berlin (12–17)Netherlands The Hague (18–19, 23)Rotterdam (20)Amsterdam (21–22)	France Alexander Alekhine	15½–9½	Weimar Republic Efim Bogoljubow	M
1934	Germany 12 cities[A]	France Alexander Alekhine	15½–10½	Germany Efim Bogoljubow	M
1935	Netherlands 12 cities	Netherlands Max Euwe	15½–14½	France Alexander Alekhine	M
1937	Netherlands 9 cities[C]	France Alexander Alekhine	15½–9½	Netherlands Max Euwe	M
Title vacant from 1946 to 1948, following the death of Alekhine.
FIDE events					M
1948	Netherlands The Hague (1–10)Soviet Union Moscow (11–20)	Soviet Union Mikhail Botvinnik	14–6	Soviet Union Vasily Smyslov	T
1951	Soviet Union Moscow	Soviet Union Mikhail Botvinnik	12–12	Soviet Union David Bronstein	M
1954	Soviet Union Moscow	Soviet Union Mikhail Botvinnik	12–12	Soviet Union Vasily Smyslov	M
1957	Soviet Union Moscow	Soviet Union Vasily Smyslov	12½–9½	Soviet Union Mikhail Botvinnik	M
1958	Soviet Union Moscow	Soviet Union Mikhail Botvinnik	12½–10½	Soviet Union Vasily Smyslov	M
1960	Soviet Union Moscow	Soviet Union Mikhail Tal	12½–8½	Soviet Union Mikhail Botvinnik	M
1961	Soviet Union Moscow	Soviet Union Mikhail Botvinnik	13–8	Soviet Union Mikhail Tal	M
1963	Soviet Union Moscow	Soviet Union Tigran Petrosian	12½–9½	Soviet Union Mikhail Botvinnik	M
1966	Soviet Union Moscow	Soviet Union Tigran Petrosian	12½–11½	Soviet Union Boris Spassky	M
1969	Soviet Union Moscow	Soviet Union Boris Spassky	12½–10½	Soviet Union Tigran Petrosian	M
1972	Iceland Reykjavík	United States Bobby Fischer	12½–8½	Soviet Union Boris Spassky	M
1975	Philippines Manila	Soviet Union Anatoly Karpov	default	United States Bobby Fischer	M
1978	Philippines Baguio	Soviet Union Anatoly Karpov	16½–15½	FIDE Viktor Korchnoi	M
1981	Italy Merano	Soviet Union Anatoly Karpov	11–7	Switzerland Viktor Korchnoi	M
1984–1985	Soviet Union Moscow	Soviet Union Anatoly Karpov	25–23	Soviet Union Garry Kasparov	M
1985	Soviet Union Moscow	Soviet Union Garry Kasparov	13–11	Soviet Union Anatoly Karpov	M
1986	United Kingdom London (1–12)Soviet Union Leningrad (13–24)	Soviet Union Garry Kasparov	12½–11½	Soviet Union Anatoly Karpov	M
1987	Spain Seville	Soviet Union Garry Kasparov	12–12	Soviet Union Anatoly Karpov	M
1990	United States New York City (1–12)France Lyon (13–24)	Russia Garry Kasparov	12½–11½	Soviet Union Anatoly Karpov	M
Classical World Chess Championships (1993–2006)
1993	United Kingdom London	Russia Garry Kasparov	12½–7½	United Kingdom Nigel Short	M
1995	United States New York City	Russia Garry Kasparov	10½–7½	India Viswanathan Anand	M
2000	United Kingdom London	Russia Vladimir Kramnik	8½–6½	Russia Garry Kasparov	M
2004‡	Switzerland Brissago	Russia Vladimir Kramnik	7–7	Hungary Peter Leko	M
FIDE World Chess Championships (1993–2006)
1993	Netherlands Zwolle (1–3)Arnhem (4–6)Amsterdam (7–12)Indonesia Jakarta (13–24)	Russia Anatoly Karpov	12½–8½	Netherlands Jan Timman	M
1996	Russia Elista	Russia Anatoly Karpov	10½–7½	United States Gata Kamsky	M
1998†	Switzerland Lausanne	Russia Anatoly Karpov	3–3, 2-0	India Viswanathan Anand	T
1999†	United States Las Vegas	Russia Alexander Khalifman	18½–11½	Armenia Vladimir Akopian	T
2000	India New Delhi (rounds 1–6)Iran Tehran (round 7)	India Viswanathan Anand	14–6	Spain Alexei Shirov	T
2002	Moscow	Ukraine Ruslan Ponomariov	19-9	Ukraine Vasyl Ivanchuk	T
2004†	Libya Tripoli	Uzbekistan Rustam Kasimdzhanov	20–10	England Michael Adams	T
2005†	Argentina Potrero de los Funes	Bulgaria Veselin Topalov	10–4	India Viswanathan Anand	T
FIDE World Championships (2006–present)
2006	Russia Elista	Russia Vladimir Kramnik	6–6, 2½–1½	Bulgaria Veselin Topalov	M
2007†	Mexico Mexico City	India Viswanathan Anand	9–5	Russia Vladimir Kramnik	T
2008	Germany Bonn	India Viswanathan Anand	6½–4½	Russia Vladimir Kramnik	M
2010	Bulgaria Sofia	India Viswanathan Anand	6½–5½	Bulgaria Veselin Topalov	M
2012	Russia Moscow	India Viswanathan Anand	6–6, 2½–1½	Israel Boris Gelfand	M
2013	India Chennai	Norway Magnus Carlsen	6½–3½	India Viswanathan Anand	M
2014	Russia Sochi	Norway Magnus Carlsen	6½–4½	India Viswanathan Anand	M
2016	United States New York City	Norway Magnus Carlsen	6–6, 3–1	Russia Sergey Karjakin	M
2018	United Kingdom London	Norway Magnus Carlsen	6–6, 3–0	United States Fabiano Caruana	M
2021	United Arab Emirates Dubai	Norway Magnus Carlsen	7½–3½	Ian Nepomniachtchi	M
2023	Kazakhstan Astana	China Ding Liren	7–7, 2½–1½	FIDE Ian Nepomniachtchi	M
2024	Singapore	India Gukesh Dommaraju	7½–6½	China Ding Liren	M

The name that appears most often is obviously Karpov, 11 times, but if you are not inclined to count the 1975 match that Fischer forfeited, then Anand also played in 10 title events, including some of the 1990s FIDE tournaments where he didn't make it to the final.

1995 PCA World Championship Match – Challenger vs. Garry Kasparov (lost)
1998 FIDE World Championship Match – Challenger vs. Karpov (lost in rapid tiebreaks)
2000 FIDE Knockout (New Delhi/Tehran) – Champion, beat Shirov
2001/02 FIDE Knockout (Moscow) – Semifinalist, lost to Ivanchuk
2005 FIDE World Championship (San Luis, double round-robin) – Participated, tied 2nd–3rd behind Topalov
2007 Unified World Championship (Mexico City, double round-robin) – Champion
2008 World Championship Match – Defended title vs. Kramnik (won)
2010 World Championship Match – Defended title vs. Topalov (won)
2012 World Championship Match – Defended title vs. Gelfand (won in rapid tiebreaks)
2013 World Championship Match – Lost title to Carlsen

If you are mostly interested in the lineal sequence of championships, ignoring FIDE's parallel track in the 1990s(*), then Karpov's 7 events come second to the 8 events of both Kasparov and Botvinnik. Some say the World Championship dates back in effect to 1866, not 1886, and if so, then Steinitz can also lay claim to 8 matches to decide who was the strongest player in the world.

(*) The 2004 FIDE event had only two of the top ten players of the day taking part.