Minsc
Minsc is a Lawful Good Ranger who can be recruited in both games. With a stength of 18/93 and a reasonable constitution, he makes a good frontline melee fighter. Although he will refuse to be in the same party as Edwin, he gets along with other party members and has some amusing dialogue options.
Baldur's Gate 1
Minsc can be found in Nashkel, where is he looking for a band of adventurers to help him rescue Dynaheir. Once recruited, you must rescue Dynaheir within a certain time limit, otherwise Minsc will leave the party. It is possible to recruit Minsc after rescuing Dynaheir, but if you talk to Minsc after recruiting Dynaheir and refuse to recruit him, Dynaheir will leave.
Baldur's Gate 2
Minsc can found near your cell at the beginning of the game. Dynaheir does not appear in BG2 so there is no requirement to recruit her in order to keep Minsc in your party.
Minsc does not have a side quest in BG2, but there is one quest which he will insist you start once you have been made aware of it.