Here's a look at tonight's sci-fi TV:
Smallville, 'Salvation' – The entire season has been leading up to this: Clark and Zod go head to head in an epic battle on tonight's season nine finale. Superfriends Hawkman (Michael Shanks), Black Canary (Alaina Huffman), Cyborg (Lee Thompson Young) and Stargirl (Britt Irvin) return to help Clark take on the Kandorians while Chloe searches for a missing Oliver. Meanwhile, Lois comes close to learning Clark's secret. (8 p.m. ET on The CW)
Stargate Universe, 'Pain' – It's space madness time on SGU as the Destiny crew begins to suffer from strange hallucinations of people from their past. T.J. works to control the spread of the visions before they lead to serious danger. (9 p.m. ET on Syfy)
Head after the jump for preview clips and more TV picks.