A pikeman was a member of the guards in San Martino. He and the other guards chased after the Fourth Doctor after he escaped being executed. When the Doctor went into the catacombs, he told his fellow he might be a worshiper of Deimos. He then added that he wouldn't go in the catacombs for all the gold in Rome, as he had known many who had tried, and were never heard from again.
He and his fellow later managed to capture the Doctor and Sarah Jane Smith at the entrance to the catacombs, and brought him to the Duke Giuliano. (TV: The Masque of Mandragora)