Boys: We have Ed, Edd, Eddie, Eddy, etc. for Edward
Andy for Andrew
Vic for Victor
Tom or Tommy for Thomas
Frank for Franklin
Nate/Nathan for Nathaniel
Nate for Nathan
Girls:
Vicky for Victoria
Andrea or Anna, I’ve seen Ann/Anne or Annie, also with Anabel/Anabelle too
Tanya for Tatyana but I don’t see many people with this name, I know one and she was my bully’s Russian mother.
Some other German ones:
Nick for Niklas and Nick/Niko for Nikolaus
Matze for Martin
Sepp for Josef
Kathi, Katta and Kadda for Katharina and Kathrin
Alex for Alexander and Alexandra
Vicki for Viktoria
Schorsch (not spoken with an English accent) for Georg
Bert for Berthold
Basti and Sebi for Sebastian
Gabi for Gabriele
Siggi for Siegfried and Sieglinde
Uschi for Ursula
And of course English nicknames for German names, e.g. Jules for Julian, Dave for David.