Multi Factor

one factor for short rate
another factor for long rate

No-Arbitrage

Hull and White (HW) (1987) - Two Factor

Heath-Jarrow-Morton (HJM) (1992)
This model is for predicting forward rates

Equilibrium

Longstaff-Schwartz (1989)

Others ??

Merton (1973)
Geometric Brownian Motion
Dothan (1978)
Courtadon (1982)
Langetieg (1980)
Richard (1979)
Black Scholes (1973)
Jarrow and Rudd (1982)
Boyle (1977) - monte carlo simulation