$re = '/^(?:\[[^\]\[\n]*\]\s+)?(?<name>[^)(\n]*)\s*(\((?!not|unus)[^)(\n]*\))?/m';
$str = '[Example] öäüß asdf 1234 (1aö)
[Red] Panda (It\'s so cute)
[Red] The Panda (It\'s so cute),
[Red] what Panda (It\'s so cute) (not necessary),
[Red] it\'s a Panda (It\'s so cute) (unusual),
[Yellow] Leopard (the big one)
[Yellow] The Leopard (the big one),
[Yellow] what Leopard (the big one) (not needed),
[Yellow] it\'s a Leopard (the big one) (unusual),
[Green] Dragon (Fire? It\'s hot!)
[Green] The Dragon (Fire? It\'s hot!),
[Green] what Dragon (Fire? It\'s hot!) (not usual),
[Green] it\'s a Dragon (Fire? It\'s hot!) (unusual),
[Blue] Snake (zzzZZZzzzZZZ)
[Blue] The Snake (zzzZZZzzzZZZ),
[Blue] what Snake (zzzZZZzzzZZZ) (not beautiful),
[Blue] it\'s a Snake (zzzZZZzzzZZZ) (unusual),
Panda (It\'s so cute)
The Panda (It\'s so cute),
what Panda (It\'s so cute) (not necessary),
it\'s a Panda (It\'s so cute) (unusual),
Leopard (the big one)
The Leopard (the big one),
what Leopard (the big one) (not usual),
it\'s a Leopard (the big one) (unusual),
Dragon (Fire? It\'s hot!)
The Dragon (Fire? It\'s hot!),
what Dragon (Fire? It\'s hot!) (not necessary),
it\'s a Dragon (Fire? It\'s hot!) (unusual),
Snake (zzzZZZzzzZZZ)
The Snake (zzzZZZzzzZZZ),
what Snake (zzzZZZzzzZZZ) (not beautiful),
it\'s a Snake (zzzZZZzzzZZZ) (unusual),
Panda
The Panda,
what Panda (not necessary),
it\'s a Panda (unusual),
Leopard
The Leopard,
what Leopard (not needed),
it\'s a Leopard (unusual),
Dragon
The Dragon,
what Dragon (not usual),
it\'s a Dragon (unusual),
Snake
The Snake ,
what Snake (not beautiful),
it\'s a Snake (unusual),';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php