Peculiar galaxies

A list of categories of galactic peculiarity, from 'A Catalogue of Southern Peculiar Galaxies and Associations' here
1. Galaxies with interacting companions
1a.Strong Interaction with Spiral Arms
1b.Strong Interaction with Main Body
1c.Wider Interactions
1d.Less Strong Interaction
2. Interacting doubles
2a.E + E Interaction
2b.E + S Interaction
2c.S + S Interaction
3. Interacting triples
3a.Simple Interacting Triples
3b.Interacting Triples which are Aligned
4. Interacting quartets
5. Interacting quintets
6. Ring galaxies
6a.Empty Rings and Displaced Nuclei
6b.Thin Rings and Centered Nuclei
6c.Irregular Rings and Possible Ring-Like Forms
7. Galaxies with jets
7a.Jets from E or E-Like Galaxies
7b.Jets from Spirals
7c.Jets from Various Kinds of Galaxies
7d.Jets from Companion Galaxies
8. Galaxies with apparent companions
8a.Galaxies with Single Apparent Companions
8b.Galaxies with Diametric Apparent Companions
8c.Galaxies with Apparent Companions which are DoubleGalaxies with Numerous Apparent Companions
9. M51-types
10. Galaxies with peculiar spiral arms
10a.E's with Faint Rings
10b.Circular (Ring) Spiral Arms and One-Armed Spirals
11. Three-armed spirals and multiple-armed spirals
12. Peculiar disks
13. Compact galaxies
14. Galaxies with prominent or unusual dust absorption
15. Galaxies with tails, loops of material or debris
16. Irregular or disturbed galaxies
17. Chains
18. Groups
19. Clusters
20. Dwarf galaxies
21. Stellar objects with associated nebulosity
22. Miscellaneous
23. Close pairs
24. Close triples
25. Planetary nebulae