A fan theory suggests Thanos will be responsible for creating Galactus, as their shared mission of cosmic balance could lead to the Fantastic Four villain's arrival in the MCU.

On Reddit, u/UpwardSpiral00 wrote about Thanos' quest to seek balance across space and time, saying that destroying the Infinity Stones after the Snap didn't make much sense.

This is because time would eventually restore the total life taken, undoing the Mad Titan's plans. Instead, they suggest Thanos created Galactus with the Infinity Stones.

Galactus would need to consume planets to maintain the population throughout the universe, which would ensure that Thanos’ work wasn’t for nothing.

Galactus would "keep life in check by [...] using burgeoning populations and biospheres for its own sustenance. A world devourer," which mortal heroes would be unable to stop.

Thanos secretly creating Galactus might be unlikely, as his comic book origin has no direct connections to him, but the theory aligns with the purpose of the Mad Titan's existence.