Norwegian Airlines has loaded low fares from Los Angeles to several Major European destinations like London, Paris, Rome, Madrid and Barcelona.
LAX to Barcelona is $399.10 round trip for travel October to April 2019 at $200 one way LAX-BCN and 170eur/$199.10usd BCN-LAX one way.
Norwegian Air LAX – Barcelona BCN – LAX
Norwegian Air LAX – Madrid MAD – LAX
2 one-way tickets ($195, 190eur/$222.53)