Here are 10 timeless software books that have significantly influenced software engineers:

1. Code: The Hidden Language of Computers
2. Working Effectively with Legacy Code
3. Refactoring: Improving the Design of Existing Code
4. Test-Driven Development
5. Head First Design Patterns
6. Algorithms to Live By
7. Git Pro
8. Your Code as a Crime Scene
9. Designing Data-Intensive Applications
10. Software Engineering at Google

Honorable mentions include Clean Code, The Pragmatic Programmer, The Soft Skills, and Peopleware.