Stowaway might work.
Hobos are supposed to do a lot of travelling like that.
There are many names, including bum, hobo, tramp, vagrant, bindlestiff, and freeloader.
A person who rides horses (mainly thoroughbreds) is called a Jockey
He rides and works with elephants. Usually in moving logs in the rain forest.
There are several synonyms for "a person who rides a horse"bronc bustercowboycavalrymanhorseguarddragoonequestrianjockey
a person who rides donkeys is called a donkey jockey
The person who rides on the back of a bike is a passenger.
a person who rides elephants is called a mahout
The person who rides a horse would be called either a equestrian or horse rider, but if the person only rides in shows, they may also be called show riders.
A bicyclist is a person who rides a bicycle.
a person who rides a bull ?!?
A ballonist.
a bicyclist
A cyclist.