LEGO® blocks, of course... but also Kre-O® blocks, Mega Bloks®, and many others!
Cobi (partly owned)
Built to Rule (2003—2005)
Self Locking Bricks (1939-?) Kiddicraft - blocks that Lego originally cloned
Tyco Super Blocks (1984-?) Tyco Toys
Guangdong Loongon, owner of the brands