One of my favourite football players, Eran Zahavi, broke the record for most goals in one season in Israel two years ago. He’s currently well on his way to break the same record in China – the most goals scored in one season in the Chinese Super League is 28 goals, and he has 22 goals with 10 games remaining.
I can’t find any players who strictly meet this criteria, but Cristiano Ronaldo certainly has a case for it. He jointly holds the record for goals scored in a 38-game Premier League season (31 goals in 2007–08), as well as having held the record for the most goals scored in La Liga, with 40 in 2010–11 (albeit only for a solitary year, as Lionel Messi scored 50 the very next season).
I specify a “38-game Premier League season” because in the early to mid 1990s, two players (Andy Cole and Alan Shearer) scored 34 goals in a single season, but they had 42 games to do this in. The Premier League officially acknowledges both of these totals as records, which means that if you found a stats book from 2011 listing the record number of goals scored in any individual season for every top-flight league, Cristiano Ronaldo’s name will probably appear twice.