There are many men in the Fellowship of the Ring, but these are the main characters.
Aragorn, son of Arathorn- He is a ranger. The Bree people started calling him Strider. He is a loyal companion of Frodo in the fellowship. He is skilled in knowing the lands and swordfighting. He is a friend of the elves. The elves call him Dunadan.
Boromir- He came to Elrond's council seeking council about a dream that he had been having about the sword (Anduril or Elendil) that cut the ring from Sauron's finger. He then joined the fellowship and planned to leave once they got to Gondor, which at that point he was to leave the fellowship. He tries to take the ring from Frodo at the end of the book because the evil powers are effecting him, and all of the rest of the fellowship.
Isildur- He is the person who cut the very ring off of Sauron's finger, and started this tale. He was easily corrupted by the ring and did not destroy it, as Elrond told him to. He was deceived by the ring, and killed by orcs trying to take it back.