Here are some more. The last one isn't out yet, but comes out in April.
Nelsen, R. B., Proofs Without Words I, II and III, MAA Press, 1997, 2000 and 2015
Sethuraman, B., Proofs and Ideas: A Prelude to Advanced Mathematics, MAA Press, 2021
Ernst, D. C., An Introduction to Proof Via...