1) Ambulance attendant, often 2) Befriender 3) Friend in need 4) Good Samaritan 5) Helper, essentially 6) Helpful one 7) Helpful sort 8) Helping hand 9) Helping one 10) Helpmate 11) Hired help 12) Legal act of help 13) Of golf 14) One giving a lift 15) One lending a helping hand 16) One who helped out 
• (n.) One who, or that which, aids.
Aid'er noun One who, or that which, aids. 
aider 1. Someone who helps. 2. An assistant, or auxiliary. 3. Someone who provides with what is useful or necessary in achieving an end.