O won the Honinbo title in 2000 and held it the following year before losing it to Kato Masao in 2002. O took the Oza title from Cho Chikun in December 2002. In July 2012, O Meien won his sixth title, the 2nd Igo Masters Cup, beating Cho Chikun.
In February 25 2010, O Meien hit the 900 landmark by beating Ko Iso in the final prelim of the 35th Kisei.
New joseki, invented by O: http://gogame.info/samples.html?id=51
O Meien is (together with Shi-Jim Yen, sensei) also in the team of the new strong Go computer program GoTrend? (March 2015).
John Fairbairn: It's Wang Mingyuan in Chinese. The last (rarish) character can be read Wan or Yuan, but Roy Schmidt met him and reports it was Yuan.
ViciousMan: Although pinyin goes for Wan, yes, Taiwan uses a different dialect, so it likely is "Yuan" in Taiwanese.
Anon: The Nihon Kiin uses Wan
Vesa Laatikainen: O Meien's non-standard opening moves are called "meienisms".