I used to have a big list of gender ambiguous names I'd use for examples. So I'd use "Alex" and "Blake" or something like that. It also had some non-anglo names on it, just to spice things up.

In comp sci papers there's a few other common example people. "I" for intruder or imposter (Irene, Isaac). "M" often for malicious or middle-person (Mal). There's a few more im forgetting now.