Keanu Reeves is born in 1964, which is generally considered the cut off point for boomers into gen X. Personally I don’t think the cutoff is as hard as that, people just before 1964 can still be raised as gen X and people born just after 1964 can be full on boomers. I like to think of the cutoff as plus minus 2 years.
In my book Keanu Reeves is gen X and not a boomer.