* MSCI world index drops off latest high as Spain weighs on Europe China Q3 GDP growth slows slightly to 6.8 pct vs 6.9 pct in Q2
* Dollar rebounds modestly thanks to spike in Treasury yields
* Brent crude flags after climbing to 3-week high
LONDON, Oct 19 (Reuters) - World stocks set a fresh record high before stalling in Europe on Thursday, as the longest winning streak for Japanese stocks since 1998 and the first close above 23,000 for Wall Street's Dow index helped to offset nerves in Spain.
Traders were marking 30 years to the day since the 1987 Black Monday stock market crash but there couldn't have been a greater contrast as equity markets have continued to clock up milestone after milestone.
The Nikkei enjoyed its 13th straight daily rise, helping the MSCI index of global stock markets - now up 17.6 percent for the year - add to its long list of record highs.
It wasn't all one-way traffic, though.
European shares took their biggest tumble in almost two months after a new batch of third-quarter results brought some disappointments, notably from Anglo-Dutch consumer goods titan Unilever, French advertising group Publicis and Germany's Kion.
They then took another lurch lower as signals emerged from Spain that Madrid was gearing up to invoke a never-before-used clause to re-impose central rule over the restive region of Catalonia.
The euro trimmed gains that had taken it to a three-day high against the dollar, while Spanish bond markets gave up their early morning gains.
"Everyone is watching this with great interest but it just looks like a standoff," said Saxo Bank FX strategist John Hardy, saying the situation was something of a 'catch-22' for Catalonia.
A declaration of independence would see it lose its prized autonomy ,while calling a regional election could mobilise Catalan voters who would prefer to stay part of Spain.
"But the market is not expressing any real fear over this and I think that is justified," Hardy added.
The other big currency market move came from the New Zealand dollar. It was sent skidding to its lowest since May after the left-leaning Labour Party won the support of the minor nationalist New Zealand First party to form a ruling coalition.
It ended weeks of political guessing games but fanned concerns that the Labour Party's hardline policies on immigrants and foreign ownership could hurt investor sentiment.
The New Zealand dollar slid as much as 1.4 percent to $0.7047, which as well as the 4-1/2 month low was also the biggest percentage decline since November 2016.
Among the other headlines, China's economic growth cooled slightly to 6.8 percent in the third quarter from a year earlier, from the second quarter's 6.9 percent.
A modest loss of momentum had been expected as the government reins in the heated property market and cracks down on riskier lending.
Other data showed that China's industrial output rose a stronger-than-expected 6.6 percent in September, while retail sales also outperformed. Property sales fell though for the first time in over two years.
The Chinese yuan and stocks eased, with Shanghai falling 0.4 percent.
"The GDP reading could weigh negatively on both mainland stocks and currency markets as traders may position for further weakness into year-end, suspecting financial curbs will continue to have a negative impact on growth in China," said Stephen Innes, head of Asia-Pacific trading at OANDA in Singapore.
The dollar index against a basket of six major currencies was broadly steady at 93.340.
The index ended a four-session winning run overnight on lacklustre U.S. data but briefly resumed its climb after the 10-year Treasury yield spiked 4 basis points with safe-haven bond prices falling on better investor risk appetite.
The dollar was little changed at 112.940 yen after climbing 0.6 percent overnight. The euro nudged up 0.15 percent to $1.1802.
The term of current Fed Chair Janet Yellen's expires in February and investors are keen to see whom U.S. President Donald Trump will pick as her replacement. The White House said Trump would announce his decision in the "coming days".
In commodities, Brent crude oil futures dropped 1.2 percent to $57.43 a barrel and U.S. WTI dropped 1.5 percent.
Brent had risen to a three-week high of $58.54 a barrel on Wednesday on worries about tensions in Iraq and Iran, but lost steam after a surprising drop in U.S. refining rates and an unexpected build in fuel stocks signalled slower demand in the world's top oil consumer. (Reporting by Marc Jones; Editing by Gareth Jones)