The first two seasons of Voltron Legendary Defender are now available on Amazon Video! You can buy access to individual episodes, or to entire seasons.
Season 1 – https://www.amazon.com/The-New-Alliance/dp/B0743NP3FD/
Season 2 – https://www.amazon.com/The-Ark-of-the-Tajueer/dp/B0743P3M4T/