Nicolaas Hendrik Christiaan de Jong Theunissen (4 May 1867 in Colesberg, Cape Colony – 9 November 1929 in Willemsdal, Greylingstad, Transvaal) was a South African cricketer who played in one Test in 1889.
Theunissen was an opening bowler who took 34 wickets in three non-first-class matches for provincial sides against the touring R.
G.
Warton's XI in 1888–89.
In the Second Test at the end of the tour he opened the bowling for South Africa but failed to take a wicket.In 1889–90 he played two first-class matches in South Africa.
In the first, he took 5 for 55 and 6 for 53 for Western Province against Natal.
In the second, which began the day after the first one ended, he took 2 for 47 and 7 for 41 for Cape Town Clubs against Natal.