Willow Page.......

Orpheus

Willow Rosenberg (Alyson Hannigan) - Willow an old friend of both Angel & Cordy is asked to help restore Angel’s Soul.For the second time .  A powerful Wiccan, Willow has the task of releasing Angel’s Soul into the Ether. After a battle with The Beast Master the ‘Muo-Ping’ (the impervious to magic globe holding Angel’s soul) is broken and Angel’s soul restored

Disharmony

Willow is an old ally of Angel’s and Cordelia’s from their days in Sunnydale.
She informs Cordelia that their old classmate Harmony Kendall is a vampire
was sired by an unknown vampire at the Graduation Battle in Buffy's Season Three 

Theres No place like Pirtz  Girtb

After  Angel and the others return from Pylea,
 Willow has the sad duty to inform Angel that Buffy died,
giving her life to save the world.

 
Oz played by Seth Green
 

Oz was sent by Buffy to give the Ring of Amarra (a ring that rendered vampires unkillable) to Angel.
 While in town, he aided in rescuing Angel from Marcus and Spike
In the Dark. 
 

Andrew Wells (Tom Lenk)

Andrew Wells (Tom Lenk) ~ Former Sunnydale geek and once member of the
 evil Troika, a reformed character who helped the Scooby gang in
Sunnydale defeat The First Evil. Since then Andrew has been in
training as a Watcher with Rupert Giles in Europe. He was sent by
Giles as his 'Top Man' to retrieve Dana, a new Slayer in Los Angeles,
who Angel had discovered. Andrew asserted his authority as a Watcher-
in-training on the slayer mythology and to oversee Dana's capture.
Andrew allowed Angel and Spike to do all the work in capturing Dana
before taking her back with him, making it clear that as far as the
Scooby's and Buffy herself were concerned, Angel was no longer working
 on the same side and that Dana was one of 'theirs'. Andrew came ready
 for a fight with 12 Slayers to make his point clear on how Angel's
new role at W&H is not trusted.