My own is obvious in that I am pretty solidly a "mule man" first in regards to equine. I have own many horses including most recently a pair of Percherons, but mules remain my first choice when riding.........Cadillac of smooth rides!
On another board I use "Lighthorseman" comes from a men's trail ride ministry I had for about 15 years called...wait for it....."Light Horsemen Ministries" ...........the original idea for me was taken from the Australian movie 'The Light Horseman" about the Australian "Light Horse Regt" in WWI. a famous mounted infantry unit. The ministry scripture reference was "Let your light
shine before men in such a way that they may see your good works, and glorify your Father who is in heaven." Matthew 5:16
On the board I have been a member of longest I use my first two initials and last name "WD Bennett" although on that forum I am likely known by many other names, most of which can't be spoken in polite company!
I remembered on another board I go by "Leatherstocking".....cause I am a big fan of James Finimore Cooper and his "Leatherstocking Tales".......Nathanial Bumpo becomes "Leatherstocking" in his senior years.