The questions
1 Which artist’s grave was marked with a black square?
2 What, significantly, was http://info.cern.ch/hypertext/WWW/TheProject.html?
3 Inaccessible Island is part of which archipelago?
4 Which writer was described as “a penis with a thesaurus”?
5 Which US first lady didn’t change her surname after marriage?
6 Who appeared at the Massabielle grotto?
7 Which gas was discovered during an 1868 total eclipse?
8 Who are Big, Little, Four-Eyed, Eat and No?
What links
9 Chinese dog; quick look; mountain top; irritation?
10 Continental; Northwest; TWA; Pan Am?
11 Emperor Frederick II; Cathars; Baltic pagans; Turks?
12 Manoj; Mallord; Mallahan; Maud; Morgan?
13 Bree; BoJack; Mister Ed?
14 TS40 tower hi-fi; CPC 464 computer; Em@iler phone?
15 Susan Sontag; Indira Gandhi; Miliband brothers; Dickie Davies?
The answers
1 Kazimir Malevich.
2 First web page address.
3 Tristan da Cunha.
4 John Updike (quoted by David Foster Wallace).
5 Eleanor Roosevelt.
6 Virgin Mary (to St Bernadette at Lourdes).
7 Helium.
8 Five guys named Moe (in song and Louis Jordan musical).
9 Homophones: Peke; peek; peak; pique.
10 Defunct American airlines.
11 All had crusades called against them.
12 Initial M in the arts: M Night Shyamalan; JMW Turner; James M Cain; LM Montgomery; EM Forster.
13 Talking horses: Chronicles of Narnia; Netflix series; TV series.
14 Amstrad products.
15 Streaks of white/grey hair.