The very first hacker purposely damaged the contact that read the value that stored if a citizen was Jewish on the punch cards of census data in occupied France (if I'm remembering correctly) it's not known how many he saved but he did pay the ultimate price and died in the concentration camps for his sabotage efforts

Edit: my memory was close. René Carmille specifically delayed the June 1941 report on the numbers of Jewish citizens and foreigners so that it still wasn't complete by the time of his ultimate arrest in 1944, and utilized his position to create extremely real fake identities for escaping refugees amongst other resistance actions